The momentum of an object changes if it accelerates or decelerates, changes ______ , or its ______ changes.

The momentum of an object changes if it accelerates or decelerates, changes direction , or its mass changes.

What is the difference between an elastic and an inelastic collision?

In an elastic collision, the objects move in opposite directions after impact. In an inelastic collision, the objects move in the same direction together , with a combined mass and velocity.

True or False? Momentum is only conserved in elastic collisions.

False. Momentum is always conserved in a collision, whether it is elastic or inelastic.

Why does a large momentum make it difficult to change an object's direction of travel?

Momentum keeps an object moving in the same direction , so a larger force is needed to change the direction of an object with greater momentum.

Define a closed system .

A closed system is one where energy is constant and there are no external forces (e.g. friction ) acting on the objects.

State the principle of conservation of momentum .

In a closed system , the total momentum before an event is equal to the total momentum after the event.

Two objects of equal mass move directly towards each other at the same speed. What is the total momentum of the system?

Zero — since momentum is a vector , the equal and opposite momenta of the two objects cancel out .

Newton's third law states that whenever two bodies interact, the forces they exert on each other are ______ and ______ .

Newton's third law states that whenever two bodies interact, the forces they exert on each other are equal and opposite .

When two objects of different mass collide, are their accelerations equal?

No — although the forces on each object are equal and opposite , acceleration also depends on mass , so objects of unequal mass have unequal accelerations .

True or False? The two forces in a Newton's third law pair act on the same object.

False. The two forces in a Newton's third law pair always act on different objects.

A ball hits a racket with the same change in momentum but over a shorter contact time than a second racket. How does this affect the force experienced?

A shorter contact time results in a greater force , since force is inversely proportional to the time taken for the momentum change.

True or False? Force and momentum are scalar quantities, so they can only be positive.

False. Force and momentum are vector quantities, so they can be positive or negative depending on direction.

Which two relationships can the force–momentum equation be derived from?

Newton's second law and the definition of acceleration .

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 a measure of an object's resistance to a change in motion .

For the same applied force, an object with a large inertial mass experiences a ______ acceleration.

For the same applied force, an object with a large inertial mass experiences a small acceleration.

Three objects experience the same applied force. Object X has the smallest acceleration. Which object has the largest inertial mass?

Object X — since inertial mass is inversely proportional to acceleration for a given force, the object with the smallest acceleration has the largest inertial mass .

GCSEPhysicsEdexcelFlashcards2. Motion & ForcesMomentum

Momentum (Edexcel GCSE Physics): Flashcards

Exam code: 1PH0

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Define momentum.

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Cards in this collection (23)

Define momentum.
Momentum (p) is the product of an object's mass and velocity: $p = m v$ , measured in kilogram metres per second (kg m/s).
What is the momentum of a stationary object, and why?
A stationary object has zero momentum, because its velocity is zero and $p = m v$ .
The momentum of an object changes if it accelerates or decelerates, changes ______, or its ______ changes.
The momentum of an object changes if it accelerates or decelerates, changes direction, or its mass changes.
What is the difference between an elastic and an inelastic collision?
In an elastic collision, the objects move in opposite directions after impact. In an inelastic collision, the objects move in the same direction together, with a combined mass and velocity.
True or False?
Momentum is only conserved in elastic collisions.
False.
Momentum is always conserved in a collision, whether it is elastic or inelastic.
A tennis ball and a brick are found to have the same momentum. What must be true about their velocities?
Since $p = m v$ , the lighter tennis ball must be travelling at a much greater speed than the heavier brick for their momenta to be equal.
Why does a large momentum make it difficult to change an object's direction of travel?
Momentum keeps an object moving in the same direction, so a larger force is needed to change the direction of an object with greater momentum.
Define a closed system.
A closed system is one where energy is constant and there are no external forces (e.g. friction) acting on the objects.
State the principle of conservation of momentum.
In a closed system, the total momentum before an event is equal to the total momentum after the event.
Two objects of equal mass move directly towards each other at the same speed. What is the total momentum of the system?
Zero — since momentum is a vector, the equal and opposite momenta of the two objects cancel out.
Newton's third law states that whenever two bodies interact, the forces they exert on each other are ______ and ______.
Newton's third law states that whenever two bodies interact, the forces they exert on each other are equal and opposite.
When two objects of different mass collide, are their accelerations equal?
No — although the forces on each object are equal and opposite, acceleration also depends on mass, so objects of unequal mass have unequal accelerations.
True or False?
The two forces in a Newton's third law pair act on the same object.
False.
The two forces in a Newton's third law pair always act on different objects.
Define force in terms of momentum.
Force is the rate of change of momentum: $F = \frac{Δ p}{Δ t}$
The change in momentum, Δp, is calculated as ______ momentum minus ______ momentum.
The change in momentum, Δp, is calculated as final momentum minus initial momentum: $Δ p = m v - m u$
A ball hits a racket with the same change in momentum but over a shorter contact time than a second racket. How does this affect the force experienced?
A shorter contact time results in a greater force, since force is inversely proportional to the time taken for the momentum change.
True or False?
Force and momentum are scalar quantities, so they can only be positive.
False.
Force and momentum are vector quantities, so they can be positive or negative depending on direction.
Which two relationships can the force–momentum equation be derived from?
Newton's second law and the definition of acceleration.
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 a measure of an object's resistance to a change in motion.
Define inertial mass.
Inertial mass is the ratio of the force applied to an object to the acceleration it experiences: $m = \frac{F}{a}$
For the same applied force, an object with a large inertial mass experiences a ______ acceleration.
For the same applied force, an object with a large inertial mass experiences a small acceleration.
True or False?
Inertial mass and the mass calculated using Newton's second law are the same quantity.
True.
Calculating mass using Newton's second law ( $F = m a$ ) is the same as calculating an object's inertial mass.
Three objects experience the same applied force. Object X has the smallest acceleration. Which object has the largest inertial mass?
Object X — since inertial mass is inversely proportional to acceleration for a given force, the object with the smallest acceleration has the largest inertial mass.

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