Mass is a measure of the amount of matter in an object; it is the property that resists change in motion.

Weight is the effect of a gravitational field on a mass; it is a force, measured in newtons (N).

An object in free fall is falling .......... under the influence of gravitational attraction.

An object in free fall is falling solely under the influence of gravitational attraction.

In the absence of air resistance, how does the acceleration of falling objects near Earth's surface compare for different masses?

All bodies fall with the same acceleration , regardless of their mass.

True or False? An object's mass decreases when it is taken to the Moon.

False. An object's mass remains the same wherever it is; only its weight changes, because the gravitational field strength differs.

Define resultant force .

The resultant force is the vector sum of all the forces acting on a body.

The acceleration of an object is always in the .......... direction as the resultant force acting on it.

The acceleration of an object is always in the same direction as the resultant force acting on it.

A resultant force acts on an object in the opposite direction to its motion. What effect does this have on the object?

The object decelerates (slows down), since the resultant force opposes the direction of motion.

True or False? The resultant force acting at an angle to an object's motion can be found by simple arithmetic addition of the forces.

False. Since force is a vector , a resultant force acting at an angle must be found using vector addition , not simple addition.

Why is momentum described as a vector quantity?

Because it has both magnitude and direction ; it can have a positive or negative value depending on the direction of motion.

A ball travelling to the right has positive momentum, so an identical ball travelling to the left has .......... momentum.

A ball travelling to the right has positive momentum, so an identical ball travelling to the left has negative momentum.

A tennis ball and a brick have equal momentum, despite the brick having a far greater mass. Explain how this is possible.

Momentum depends on both mass and velocity ; the tennis ball has a much lower mass but a much greater velocity than the brick, so their products ( mv ) are equal.

True or False? An object with a greater mass will always have greater momentum than a lighter object.

False. Momentum depends on the product of mass and velocity, not mass alone; a lighter, faster object can have the same or greater momentum than a heavier, slower one.

For a given change in momentum, increasing the .......... taken for an impact decreases the force exerted.

For a given change in momentum, increasing the time taken for an impact decreases the force exerted.

A car exerts a force of 300 N on a wall during a collision. State the magnitude and direction of the force the wall exerts on the car.

The wall exerts a force of 300 N on the car, in the opposite direction to the force the car exerts on the wall (Newton's third law).

Define Newton's first law of motion.

A body will remain at rest or move with constant velocity unless acted on by a resultant force .

Define Newton's third law of motion.

Whenever two bodies interact, the forces they exert on each other are equal in magnitude and opposite in direction.

State the four conditions required for a pair of forces to be a Newton's third law force pair.

Same type of force Same magnitude Opposite in direction Acting on different objects

If the forces acting on an object are balanced, the object is said to be in .......... .

If the forces acting on an object are balanced, the object is said to be in equilibrium .

True or False? Two equal and opposite forces acting on the same object form a Newton's third law pair.

False. A Newton's third law pair must act on different objects ; two equal and opposite forces on the same object (e.g. weight and normal contact force) are an example of equilibrium (Newton's first law), not the third law.

A LevelPhysicsCambridge (CIE)Flashcards3. DynamicsMomentum & Newton’s Laws of Motion

Momentum & Newton’s Laws of Motion (Cambridge (CIE) A Level Physics): Flashcards

Exam code: 9702

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FrontMass & Weight
Define mass.
FrontMass & Weight
State the equation for weight, including the unit of each quantity.
BackMass & Weight
$W = m g$
W = weight in newtons (N)
m = mass in kilograms (kg)
g = acceleration of free fall in metres per second squared (m s^-2)

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Cards in this collection (27)

Define mass.
Mass is a measure of the amount of matter in an object; it is the property that resists change in motion.
Define weight.
Weight is the effect of a gravitational field on a mass; it is a force, measured in newtons (N).
State the equation for weight, including the unit of each quantity.
$W = m g$
- W = weight in newtons (N)
- m = mass in kilograms (kg)
- g = acceleration of free fall in metres per second squared (m s^-2)
An object in free fall is falling .......... under the influence of gravitational attraction.
An object in free fall is falling solely under the influence of gravitational attraction.
In the absence of air resistance, how does the acceleration of falling objects near Earth's surface compare for different masses?
All bodies fall with the same acceleration, regardless of their mass.
True or False?
An object's mass decreases when it is taken to the Moon.
False.
An object's mass remains the same wherever it is; only its weight changes, because the gravitational field strength differs.
Define resultant force.
The resultant force is the vector sum of all the forces acting on a body.
State the equation relating force, mass and acceleration, including units.
$F = m a$
- F = force in newtons (N)
- m = mass in kilograms (kg)
- a = acceleration in metres per second squared (m s^-2)
The acceleration of an object is always in the .......... direction as the resultant force acting on it.
The acceleration of an object is always in the same direction as the resultant force acting on it.
A resultant force acts on an object in the opposite direction to its motion. What effect does this have on the object?
The object decelerates (slows down), since the resultant force opposes the direction of motion.
True or False?
The resultant force acting at an angle to an object's motion can be found by simple arithmetic addition of the forces.
False.
Since force is a vector, a resultant force acting at an angle must be found using vector addition, not simple addition.
Define linear momentum.
Linear momentum is the product of an object's mass and velocity: $p = m v$ , measured in kilogram metres per second (kg m s^-1).
Why is momentum described as a vector quantity?
Because it has both magnitude and direction; it can have a positive or negative value depending on the direction of motion.
A ball travelling to the right has positive momentum, so an identical ball travelling to the left has .......... momentum.
A ball travelling to the right has positive momentum, so an identical ball travelling to the left has negative momentum.
A tennis ball and a brick have equal momentum, despite the brick having a far greater mass. Explain how this is possible.
Momentum depends on both mass and velocity; the tennis ball has a much lower mass but a much greater velocity than the brick, so their products (mv) are equal.
True or False?
An object with a greater mass will always have greater momentum than a lighter object.
False.
Momentum depends on the product of mass and velocity, not mass alone; a lighter, faster object can have the same or greater momentum than a heavier, slower one.
Define force in terms of momentum.
Force is the rate of change of momentum: $F = \frac{Δ p}{Δ t}$
State the equation for change in momentum.
$Δ p = p_{f} - p_{i}$ where p_f is the final momentum and p_i is the initial momentum.
For a given change in momentum, increasing the .......... taken for an impact decreases the force exerted.
For a given change in momentum, increasing the time taken for an impact decreases the force exerted.
A car exerts a force of 300 N on a wall during a collision. State the magnitude and direction of the force the wall exerts on the car.
The wall exerts a force of 300 N on the car, in the opposite direction to the force the car exerts on the wall (Newton's third law).
True or False?
Increasing the time over which a collision occurs, for the same change in momentum, increases the force experienced.
False.
Increasing the time decreases the force experienced, since $F = \frac{Δ p}{Δ t}$
Define Newton's first law of motion.
A body will remain at rest or move with constant velocity unless acted on by a resultant force.
Define Newton's second law of motion.
A resultant force acting on a body causes a change in the body's motion in the direction of the force: $F = m a$
Define Newton's third law of motion.
Whenever two bodies interact, the forces they exert on each other are equal in magnitude and opposite in direction.
State the four conditions required for a pair of forces to be a Newton's third law force pair.
- Same type of force
- Same magnitude
- Opposite in direction
- Acting on different objects
If the forces acting on an object are balanced, the object is said to be in ...........
If the forces acting on an object are balanced, the object is said to be in equilibrium.
True or False?
Two equal and opposite forces acting on the same object form a Newton's third law pair.
False.
A Newton's third law pair must act on different objects; two equal and opposite forces on the same object (e.g. weight and normal contact force) are an example of equilibrium (Newton's first law), not the third law.

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