A force is a push or a pull that acts on an object due to its interaction with another object. Forces can change an object's size , shape or motion (its speed or direction).

True or False? Balanced forces produce a resultant force .

False. Unbalanced forces produce a resultant force .

What is a resultant force ?

A resultant force is a single force that represents the combined effect of all the forces acting on an object. It determines both the direction and the magnitude of the overall force on the object.

State the two possible outcomes when forces combine.

Forces can combine to produce either balanced or unbalanced forces.

Define balanced forces .

Balanced forces are forces acting on an object that are equal in magnitude and opposite in direction, so there is no resultant force on the object.

When do unbalanced forces occur?

Unbalanced forces occur when the forces on an object are unequal in magnitude or not opposite in direction. This produces a resultant force that changes the object's motion.

An object is travelling forward at a constant speed in a straight line. A force is applied perpendicular to the direction of the object's motion. What is the effect on the object's motion?

A force applied perpendicular to the object's motion makes it change direction .

An object is travelling forward at a constant speed in a straight line. What is the effect on its motion if a forward-acting force is applied?

A forward-acting force makes the object speed up (accelerate).

True or False? Newton's first law states that objects will continue to move at the same velocity even if a resultant force acts on them.

False. Newton's first law states that objects continue to move at the same velocity only when there is no resultant force acting on them.

What is the effect of a zero resultant force on an object's motion?

An object with zero resultant force will: remain stationary if it is at rest continue at the same velocity if it is already moving

Define constant velocity .

Constant velocity means moving at a steady speed in a straight line , with no change in speed or direction.

In what situation does an object experience no resultant force ?

An object experiences no resultant force when the forces acting on it are balanced , so the net force is zero.

A car moves at a constant velocity . How does the frictional force compare with the driving force?

The frictional force is equal to the driving force, because the forces are balanced when the car moves at constant velocity.

State Newton's first law of motion.

Newton's first law states that objects will remain at rest, or move with a constant velocity , unless acted on by a resultant force .

When a non-zero resultant force acts on an object, what are the two possible changes in its motion?

A non-zero resultant force can change the object's: speed direction

Define Newton's second law of motion . (Extended Tier Only)

Newton's second law states that the acceleration of an object is proportional to the resultant force acting on it and inversely proportional to the object's mass.

True or False? Newton's second law states that acceleration is directly proportional to the object's mass. (Extended Tier Only)

False. Acceleration is directly proportional to the resultant force and inversely proportional to the object's mass.

How does Newton's second law build on Newton's first law ? (Extended Tier Only)

Newton's first law says an object's motion changes when a resultant force acts on it; Newton's second law describes that change — the size of the acceleration produced.

State the relationship between mass and acceleration according to Newton's second law. (Extended Tier Only)

Acceleration is inversely proportional to mass — for the same resultant force, a larger mass has a smaller acceleration .

According to Newton's second law, what is the effect on acceleration of increasing the resultant force on an object? (Extended Tier Only)

Increasing the resultant force increases the acceleration by the same factor, because they are directly proportional .

Define extension . (Extended Tier Only)

Extension is the increase in length of a spring when a force is applied, found by subtracting the original length from the final length .

In the spring investigation, what are the independent and dependent variables? (Extended Tier Only)

Independent variable = force applied to the spring Dependent variable = extension of the spring

The masses are removed and the whole experiment is repeated three times so that an ______ length can be calculated. (Extended Tier Only)

The masses are removed and the whole experiment is repeated three times so that an average length can be calculated.

On a force–extension graph, what does a straight line through the origin show? (Extended Tier Only)

It shows that the force is directly proportional to the extension , so the spring obeys Hooke's law.

True or False? Ruler measurements should be taken at eye level to avoid a parallax error. (Extended Tier Only)

True. Reading the ruler at eye level avoids a parallax error , which is a type of systematic error .

Why is a pointer attached to the bottom of the spring? (Extended Tier Only)

A pointer lets the extension be read from the ruler more precisely, reducing random error .

Define Hooke's Law . (Extended Tier Only)

Hooke's law states that the extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality .

True or False? Hooke's law states that the extension of a spring is inversely proportional to the applied force. (Extended Tier Only)

False. Hooke's law states that the extension of a spring is directly proportional to the applied force.

What is the spring constant ? (Extended Tier Only)

The spring constant (k) is the force per unit extension . It measures how stiff a spring is — a stiff spring has a high spring constant.

True or False? The spring constant (k) has units of N/kg . (Extended Tier Only)

False. The spring constant (k) has units of N/m (newtons per metre).

Friction is a force that acts in opposition to an object's motion and transfers energy by heating .

True or False? Friction speeds up the motion of an object.

False. Friction opposes the motion of an object, slowing it down.

True or False? Friction increases the temperature of an object.

True. Friction causes heating , which raises the temperature of the object and its surroundings.

What causes friction between two solid surfaces ?

Friction in solids is caused by imperfections in the surfaces of the objects moving over one another.

Fluids are substances whose particles are free to move around. Gases and liquids are fluids.

Drag is the frictional force acting on an object moving through a fluid, caused by collisions with the gas or liquid particles.

True or False? Air resistance is a type of friction.

True. Air resistance is a type of friction that slows the motion of an object moving through the air.

How does air resistance affect the temperature of an object?

Air resistance increases the object's temperature by heating , caused by work done against friction as air particles collide with the object.

State one way to reduce friction between two solid surfaces, and one way to reduce friction on an object moving through a fluid.

Friction between solid surfaces can be reduced by lubricating or smoothing them. Friction on an object moving through a fluid can be reduced by streamlining its shape.

A moment is the turning effect of a force about a pivot.

True or False? Moments cause motion.

False. Moments describe the turning effect of forces about a pivot. A resultant force is what causes motion.

True or False? To reduce the force needed to produce a moment, the distance from the pivot must be decreased.

False. To reduce the force needed to produce a moment, the distance from the pivot must be increased .

State the principle of moments . (Extended Tier Only)

For an object that is balanced , the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot.

True or False? The principle of moments applies to unbalanced systems. (Extended Tier Only)

False. The principle of moments applies only to balanced systems.

True or False? See-saws and beams are systems that use the principle of moments . (Extended Tier Only)

True. See-saws and balanced beams are systems that use the principle of moments .

Equilibrium is a state of balance in which an object stays as it is, because the forces and moments acting on it are balanced.

State the two conditions for an object to be in equilibrium .

The forces are balanced, so there is no resultant force The total clockwise moment equals the total anticlockwise moment , so there is no resultant moment

True or False? An object in equilibrium must be stationary .

False. An object in equilibrium can be stationary or moving at constant velocity .

True or False? A system in equilibrium has a resultant force acting on it.

False. A system in equilibrium has no resultant force ; the forces on it are balanced.

Define the resultant moment .

The resultant moment is the overall turning effect from all the moments acting on an object.

Define centre of gravity .

The centre of gravity of an object is the point through which the weight of the object acts.

IGCSEScienceCambridge (CIE)Co-ordinated Sciences (Double Award)PhysicsFlashcards1. Motion, Forces & EnergyEffects of Forces

Effects of Forces (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award): Physics): Flashcards

Exam code: 0654 & 0973

1/72

0Still learning

Know0

FrontResultant Forces
Define force.

Was this flashcard helpful?

Cards in this collection (72)

Define force.
A force is a push or a pull that acts on an object due to its interaction with another object. Forces can change an object's size, shape or motion (its speed or direction).
True or False?
Balanced forces produce a resultant force.
False.
Unbalanced forces produce a resultant force.
What is a resultant force?
A resultant force is a single force that represents the combined effect of all the forces acting on an object. It determines both the direction and the magnitude of the overall force on the object.
State the two possible outcomes when forces combine.
Forces can combine to produce either balanced or unbalanced forces.
Define balanced forces.
Balanced forces are forces acting on an object that are equal in magnitude and opposite in direction, so there is no resultant force on the object.
When do unbalanced forces occur?
Unbalanced forces occur when the forces on an object are unequal in magnitude or not opposite in direction. This produces a resultant force that changes the object's motion.
An object is travelling forward at a constant speed in a straight line. A force is applied perpendicular to the direction of the object's motion. What is the effect on the object's motion?
A force applied perpendicular to the object's motion makes it change direction.
An object is travelling forward at a constant speed in a straight line. What is the effect on its motion if a forward-acting force is applied?
A forward-acting force makes the object speed up (accelerate).
Two forces act on a box along the same straight line: 7 N to the left and 3 N to the right. What is the resultant force?
Taking forces to the right as positive and to the left as negative, the resultant force is:
$(- 7) + 3 = - 4 N$
The resultant force is 4 N to the left.
True or False?
Newton's first law states that objects will continue to move at the same velocity even if a resultant force acts on them.
False.
Newton's first law states that objects continue to move at the same velocity only when there is no resultant force acting on them.
What is the effect of a zero resultant force on an object's motion?
An object with zero resultant force will:
- remain stationary if it is at rest
- continue at the same velocity if it is already moving
Define constant velocity.
Constant velocity means moving at a steady speed in a straight line, with no change in speed or direction.
In what situation does an object experience no resultant force?
An object experiences no resultant force when the forces acting on it are balanced, so the net force is zero.
A car moves at a constant velocity. How does the frictional force compare with the driving force?
The frictional force is equal to the driving force, because the forces are balanced when the car moves at constant velocity.
State Newton's first law of motion.
Newton's first law states that objects will remain at rest, or move with a constant velocity, unless acted on by a resultant force.
When a non-zero resultant force acts on an object, what are the two possible changes in its motion?
A non-zero resultant force can change the object's:
- speed
- direction
Define Newton's second law of motion. (Extended Tier Only)
Newton's second law states that the acceleration of an object is proportional to the resultant force acting on it and inversely proportional to the object's mass.
True or False?
Newton's second law states that acceleration is directly proportional to the object's mass. (Extended Tier Only)
False.
Acceleration is directly proportional to the resultant force and inversely proportional to the object's mass.
How does Newton's second law build on Newton's first law? (Extended Tier Only)
Newton's first law says an object's motion changes when a resultant force acts on it; Newton's second law describes that change — the size of the acceleration produced.
What is the equation for Newton's second law? (Extended Tier Only)
$F = m a$
Where:
- $F$ = resultant force, measured in newtons (N)
- $m$ = mass, measured in kilograms (kg)
- $a$ = acceleration, measured in metres per second squared (m/s²)
True or False?
In the equation $F = m a$ , the force and acceleration act in opposite directions. (Extended Tier Only)
False.
In the equation $F = m a$ , the force and acceleration act in the same direction.
State the relationship between mass and acceleration according to Newton's second law. (Extended Tier Only)
Acceleration is inversely proportional to mass — for the same resultant force, a larger mass has a smaller acceleration.
According to Newton's second law, what is the effect on acceleration of increasing the resultant force on an object? (Extended Tier Only)
Increasing the resultant force increases the acceleration by the same factor, because they are directly proportional.
Define extension. (Extended Tier Only)
Extension is the increase in length of a spring when a force is applied, found by subtracting the original length from the final length.
In the spring investigation, what are the independent and dependent variables? (Extended Tier Only)
- Independent variable = force applied to the spring
- Dependent variable = extension of the spring
How is the force on the spring calculated from the hanging masses? (Extended Tier Only)
The force equals the weight of the masses, calculated using $W = m g$ with $g = 9.8 N/kg$ (multiply each mass in kg by 9.8).
The masses are removed and the whole experiment is repeated three times so that an ______ length can be calculated. (Extended Tier Only)
The masses are removed and the whole experiment is repeated three times so that an average length can be calculated.
On a force–extension graph, what does a straight line through the origin show? (Extended Tier Only)
It shows that the force is directly proportional to the extension, so the spring obeys Hooke's law.
True or False?
Ruler measurements should be taken at eye level to avoid a parallax error. (Extended Tier Only)
True.
Reading the ruler at eye level avoids a parallax error, which is a type of systematic error.
Why is a pointer attached to the bottom of the spring? (Extended Tier Only)
A pointer lets the extension be read from the ruler more precisely, reducing random error.
Define Hooke's Law. (Extended Tier Only)
Hooke's law states that the extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality.
What is the equation for Hooke's law? (Extended Tier Only)
$F = k x$
Where:
- $F$ = force applied, measured in newtons (N)
- $k$ = spring constant, measured in newtons per metre (N/m)
- $x$ = extension of the spring, measured in metres (m)
True or False?
Hooke's law states that the extension of a spring is inversely proportional to the applied force. (Extended Tier Only)
False.
Hooke's law states that the extension of a spring is directly proportional to the applied force.
What is the spring constant? (Extended Tier Only)
The spring constant (k) is the force per unit extension. It measures how stiff a spring is — a stiff spring has a high spring constant.
True or False?
The spring constant (k) has units of N/kg. (Extended Tier Only)
False.
The spring constant (k) has units of N/m (newtons per metre).
What does the green arrow represent on this force-extension graph? (Extended Tier Only)
The green arrow shows the linear portion of the graph. This is where the spring obeys Hooke's law, so force and extension are directly proportional.
What does the green arrow represent on this force-extension graph? (Extended Tier Only)
The green arrow shows the non-linear portion of the graph. Here the spring does not obey Hooke's law, so force and extension are no longer proportional.
What does the red cross represent on this force-extension graph? (Extended Tier Only)
The red cross represents the limit of proportionality. Beyond this point, force and extension are no longer directly proportional.
Define friction.
Friction is a force that acts in opposition to an object's motion and transfers energy by heating.
True or False?
Friction speeds up the motion of an object.
False.
Friction opposes the motion of an object, slowing it down.
True or False?
Friction increases the temperature of an object.
True.
Friction causes heating, which raises the temperature of the object and its surroundings.
What causes friction between two solid surfaces?
Friction in solids is caused by imperfections in the surfaces of the objects moving over one another.
Define fluids.
Fluids are substances whose particles are free to move around. Gases and liquids are fluids.
Define drag.
Drag is the frictional force acting on an object moving through a fluid, caused by collisions with the gas or liquid particles.
True or False?
Air resistance is a type of friction.
True.
Air resistance is a type of friction that slows the motion of an object moving through the air.
How does air resistance affect the temperature of an object?
Air resistance increases the object's temperature by heating, caused by work done against friction as air particles collide with the object.
State one way to reduce friction between two solid surfaces, and one way to reduce friction on an object moving through a fluid.
Friction between solid surfaces can be reduced by lubricating or smoothing them.
Friction on an object moving through a fluid can be reduced by streamlining its shape.
Define a moment.
A moment is the turning effect of a force about a pivot.
True or False?
Moments cause motion.
False.
Moments describe the turning effect of forces about a pivot. A resultant force is what causes motion.
What is the equation for the moment of a force?
$M = F \times d$
Where:
- $M$ = moment, in newton metres (N m)
- $F$ = force, in newtons (N)
- $d$ = perpendicular distance from the pivot, in metres (m)
True or False?
Rearranged for the perpendicular distance from the pivot, the moment equation is $d = \frac{F}{M}$
False.
Rearranged for the perpendicular distance from the pivot, the moment equation is $d = \frac{M}{F}$
True or False?
To reduce the force needed to produce a moment, the distance from the pivot must be decreased.
False.
To reduce the force needed to produce a moment, the distance from the pivot must be increased.
A force of 3 N is applied at a perpendicular distance of 0.5 m from a pivot. Calculate the moment of the force.
The moment of the force is 1.5 N m.
$M = F \times d = 3 \times 0.5 = 1.5 N m$
State the principle of moments. (Extended Tier Only)
For an object that is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot.
True or False?
The principle of moments applies to unbalanced systems. (Extended Tier Only)
False.
The principle of moments applies only to balanced systems.
True or False?
See-saws and beams are systems that use the principle of moments. (Extended Tier Only)
True.
See-saws and balanced beams are systems that use the principle of moments.
Define equilibrium.
Equilibrium is a state of balance in which an object stays as it is, because the forces and moments acting on it are balanced.
State the two conditions for an object to be in equilibrium.
- The forces are balanced, so there is no resultant force
- The total clockwise moment equals the total anticlockwise moment, so there is no resultant moment
True or False?
An object in equilibrium must be stationary.
False.
An object in equilibrium can be stationary or moving at constant velocity.
True or False?
A system in equilibrium has a resultant force acting on it.
False.
A system in equilibrium has no resultant force; the forces on it are balanced.
Define the resultant moment.
The resultant moment is the overall turning effect from all the moments acting on an object.
Define centre of gravity.
The centre of gravity of an object is the point through which the weight of the object acts.
True or False?
The centre of gravity is always located at the geometric centre of an object.
False.
The centre of gravity is at the geometric centre only for a symmetrical object of uniform density. For an irregular object it can lie elsewhere.
Define stability.
Stability is a measure of how difficult it is to make an object topple over.
True or False?
An object is stable when its centre of gravity is below its base.
False.
An object is stable when its centre of gravity lies above its base. If it does not, the object will topple over.
What makes an object more stable?
An object is more stable when it has a low centre of gravity and a wide base.
When will an object topple over?
An object topples when the line of action of its weight falls outside its base, creating a resultant moment that turns it over.
Where does an object's centre of gravity come to rest when it is suspended and left to settle?
When an object is suspended and allowed to settle, its centre of gravity comes to rest directly below the point of suspension.
True or False?
A plumb line is used to mark a vertical line on the lamina.
True.
A plumb line hangs vertically, so it marks the vertical line of action of the weight from the point of suspension.
How can you find the centre of gravity of an irregular plane lamina?
Suspend the lamina from three different points. Use a plumb line to mark the vertical line each time. The point where the lines cross is the centre of gravity.
Why should the holes be punched in the lamina before finding the lines of action of the weight?
Punching the holes after could change the position of the centre of gravity, so the holes are punched first.
How should the plumb line be viewed to reduce error?
The plumb line should be viewed straight on to avoid a parallax error.

Sign up to unlock flashcards

By signing up you agree to our Terms and Privacy Policy

Previous:Mass, Weight & DensityNext:Energy, Work & Power