Newton's Laws of Motion (AQA GCSE Physics): Flashcards
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- FrontNewton's First Law
Define Newton's first law of motion.
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Cards in this collection (33)
Define Newton's first law of motion.
Objects will remain at rest, or move with a constant velocity, unless acted on by a resultant force.
What happens to the velocity of an object if a resultant force acts on it?
Its velocity will change — either its speed, its direction, or both.
According to Newton's first law, what can you conclude about the resultant force on an object that is at rest or moving at a constant velocity?
No resultant force is acting on it.
A constant velocity means there is no change in ______ and no change in ______.
A constant velocity means there is no change in speed and no change in direction.
A comet moves through space at a constant velocity. What does this tell you about the forces acting on it?
The forces on the comet are balanced, so the resultant force is zero.
True or False?
The Moon orbiting the Earth at a constant speed is an example of Newton's first law of motion.
False.
The Moon's direction continually changes as it orbits, so it is not moving at a constant velocity — Newton's first law requires no change in speed or direction.
Define Newton's second law of motion.
The acceleration of an object is proportional to the resultant force acting on it, and inversely proportional to the object's mass.
For a given resultant force, the greater the object's mass, the ______ the acceleration experienced.
For a given resultant force, the greater the object's mass, the smaller the acceleration experienced.
Write the equation linking force, mass and acceleration, stating the meaning of each symbol.
F = m a, where F = resultant force (N), m = mass (kg), a = acceleration (m/s²).
Three shopping trolleys of different masses are each pushed with the same force. Which trolley has the smallest acceleration? Explain your answer.
The trolley with the greatest mass. Acceleration is inversely proportional to mass, so for the same force a larger mass produces a smaller acceleration.
A car has a mass of 900 kg and accelerates from 0 to 27 m/s in 3 seconds. Calculate the resultant force needed to produce this acceleration.
a = 27 ÷ 3 = 9 m/s²
F = m a = 900 × 9 = 8100 N
What symbol is used to show that a value in a calculation is an estimate?
The symbol ~ (approximately equal to).
True or False?
For a given resultant force, an object with a greater mass will experience a greater acceleration.
False.
For a given force, a greater mass results in a smaller acceleration — acceleration is inversely proportional to mass.
In Experiment 1 of this required practical, what is the independent variable?
Force, F, applied to the trolley (varied by changing the masses on the weight hanger).
In Experiment 1 of this required practical, what variable must be controlled (kept constant)?
The total mass, m, of the trolley and weight system.
In Experiment 2 of this required practical, what is the independent variable?
The mass, m, on the trolley.
In this required practical, acceleration is calculated using the equation: acceleration = ______ ÷ time taken.
In this required practical, acceleration is calculated using the equation: acceleration = change in velocity ÷ time taken.
In Experiment 1, why must masses removed from the weight hanger be placed onto the trolley?
To keep the total mass of the system constant, avoiding a systematic error.
What is the resolution of the stopwatch used in this required practical?
0.01 s
Why should the trolley be released rather than given a push at the start of each timing?
A push would add an uncontrolled extra force, introducing a random error into the timing measurements.
True or False?
Using large masses on the weight hanger makes the time measurements in this required practical more accurate.
False.
Small masses should be used so the trolley moves at a relatively slow pace, making the time measurements more accurate.
Define Newton's third law of motion.
Whenever two bodies interact, the forces they exert on each other are equal and opposite.
What two conditions, based on the objects involved and the forces themselves, identify a Newton's third law force pair?
(1) The two forces act on different objects
(2) The two forces are equal in size but opposite in direction
Newton's third law force pairs are always of the ______ type of force.
Newton's third law force pairs are always of the same type of force.
A foot pushes down on the ground while walking. According to Newton's third law, what force does the ground exert on the foot?
An equal and opposite push force on the foot, of the same type.
True or False?
The vector diagram showing weight and normal contact force acting on a book resting on a table is an example of Newton's third law.
False.
It is an example of Newton's first law — both forces act on the same object (the book) and are not the same type of force.
A book rests on a table. What are the two correct Newton's third law force pairs in this scenario?
(1) The gravitational pull of the Earth on the book, paired with the gravitational pull of the book on the Earth
(2) The normal contact force of the table on the book, paired with the normal contact force of the book on the table
Define inertia.
Inertia is the tendency of an object to continue in its state of rest, or in uniform motion, unless acted on by an external force. It is an object's resistance to a change in motion.
Define inertial mass.
Inertial mass is the property of an object that describes how difficult it is to change its velocity. It is the ratio of the force applied to an object to the acceleration it experiences.
Write the equation that defines inertial mass, stating the meaning of each symbol.
m = F/a, where m = inertial mass (kg), F = force (N), a = acceleration (m/s²).
For a given force, an object with a ______ inertial mass will accelerate more slowly.
For a given force, an object with a larger inertial mass will accelerate more slowly.
The same force is applied to three objects, A, B and C. Object A accelerates at 1.5 m/s², Object B at 0.7 m/s², and Object C at 2.0 m/s². Which object has the largest inertial mass?
Object B, because it has the smallest acceleration for the same applied force, and inertial mass is inversely proportional to acceleration.
True or False?
A moving object with a large inertial mass will speed up quickly for a given force.
False.
A large inertial mass makes an object harder to accelerate, so it speeds up more slowly.
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