Online Quiz On Momentum

1. What impulse occurs when an average force of 15 N is exerted on a cart for 3.0 s?

55 N.s

50 N.s

45 N.s

40 N.s

The impulse experienced by an object is equal to the product of the average force exerted on it and the time interval over which the force is applied. In this case, the average force is 15 N and the time interval is 3.0 s. Therefore, the impulse can be calculated by multiplying the force and time: 15 N x 3.0 s = 45 N.s.

Explanation

The impulse experienced by an object is equal to the product of the average force exerted on it and the time interval over which the force is applied. In this case, the average force is 15 N and the time interval is 3.0 s. Therefore, the impulse can be calculated by multiplying the force and time: 15 N x 3.0 s = 45 N.s.

2. What could be the momentum of a 1,300-kg car that moves at 4 m/s?

5,200 N

5,200 kg.m/s

52 kg.m/s

52 N

The momentum of an object is calculated by multiplying its mass and velocity. In this question, the mass of the car is given as 1,300 kg and its velocity is given as 4 m/s. Therefore, the momentum can be calculated as 1,300 kg * 4 m/s = 5,200 kg.m/s.

Explanation

The momentum of an object is calculated by multiplying its mass and velocity. In this question, the mass of the car is given as 1,300 kg and its velocity is given as 4 m/s. Therefore, the momentum can be calculated as 1,300 kg * 4 m/s = 5,200 kg.m/s.

3. Why is falling on a floor with more give less dangerous than falling on a floor with less give?

Because the floor with more give allows a greater time for the impulse that reduces the momentum of fall to zero. A greater time for a change in momentum results in less force.

Because falling on a floor with more give causes less impact.

Because falling on a floor with more give includes greater momentum.

Because falling on a floor with less give comprises shorter time.

Falling on a floor with more give is less dangerous because it allows for a greater time for the impulse that reduces the momentum of the fall to zero. This means that there is a longer period of time for the change in momentum to occur, resulting in less force being exerted on the body. In contrast, falling on a floor with less give would result in a shorter time for the change in momentum, leading to a higher force and potentially more severe injuries.

Explanation

Falling on a floor with more give is less dangerous because it allows for a greater time for the impulse that reduces the momentum of the fall to zero. This means that there is a longer period of time for the change in momentum to occur, resulting in less force being exerted on the body. In contrast, falling on a floor with less give would result in a shorter time for the change in momentum, leading to a higher force and potentially more severe injuries.

4. Newton's second law states that of no net force is exerted on a system, no acceleration occurs. Does it follow that no change in momentum occurs?

No, other variables can lead to the change in speed other than acceleration.

Yes, because no acceleration means that no change occurs in velocity or in momentum.

Yes, because according to Newton's second law, if no net force is exerted on a system, there is no acceleration. Since acceleration is the rate of change of velocity, if there is no acceleration, there is no change in velocity. And since momentum is directly proportional to velocity, if there is no change in velocity, there is no change in momentum. Therefore, if no net force is exerted on a system, no change in momentum occurs.

Explanation

Yes, because according to Newton's second law, if no net force is exerted on a system, there is no acceleration. Since acceleration is the rate of change of velocity, if there is no acceleration, there is no change in velocity. And since momentum is directly proportional to velocity, if there is no change in velocity, there is no change in momentum. Therefore, if no net force is exerted on a system, no change in momentum occurs.

5. Will a large truck always have more momentum than a roller skate?

No, a large truck at rest has no momentum. A moving roller skate has momentum.

Yes, a large truck has greater mass than a a roller skate.

The explanation for the given answer is that momentum is defined as the product of an object's mass and its velocity. Even though a large truck has greater mass than a roller skate, if the truck is at rest, its velocity is zero, resulting in zero momentum. On the other hand, a moving roller skate has both mass and velocity, therefore it has momentum. Thus, it is not always true that a large truck will have more momentum than a roller skate.

Explanation

The explanation for the given answer is that momentum is defined as the product of an object's mass and its velocity. Even though a large truck has greater mass than a roller skate, if the truck is at rest, its velocity is zero, resulting in zero momentum. On the other hand, a moving roller skate has both mass and velocity, therefore it has momentum. Thus, it is not always true that a large truck will have more momentum than a roller skate.

6. Read the following statement :"If no net force or net impulse acts on a system, the momentum of that system cannot change." What does it refer to?

Law of Impulse

Newton's 3rd Law

Law of Momentum

Law of Conservation of Momentum

The statement refers to the Law of Conservation of Momentum. This law states that if there is no net external force acting on a system, the total momentum of the system remains constant. In other words, the momentum before an event is equal to the momentum after the event, as long as no external forces are present. This law is a fundamental principle in physics and is used to analyze and predict the motion of objects in various scenarios.

Explanation

The statement refers to the Law of Conservation of Momentum. This law states that if there is no net external force acting on a system, the total momentum of the system remains constant. In other words, the momentum before an event is equal to the momentum after the event, as long as no external forces are present. This law is a fundamental principle in physics and is used to analyze and predict the motion of objects in various scenarios.

7. Momentum means or is most associated with:

Inertia

Newton's second Law

Inertia in Motion

Impulse

Momentum is most associated with "Inertia in Motion" because momentum is a property of moving objects and is defined as the product of an object's mass and velocity. Inertia, on the other hand, refers to an object's resistance to changes in its motion, whether it is at rest or in motion. Therefore, the combination of inertia and motion accurately represents the concept of momentum. Newton's second law relates force, mass, and acceleration, while impulse refers to the change in momentum of an object.

Explanation

Momentum is most associated with "Inertia in Motion" because momentum is a property of moving objects and is defined as the product of an object's mass and velocity. Inertia, on the other hand, refers to an object's resistance to changes in its motion, whether it is at rest or in motion. Therefore, the combination of inertia and motion accurately represents the concept of momentum. Newton's second law relates force, mass, and acceleration, while impulse refers to the change in momentum of an object.

8. Based on the problem above, if the mass of the cart is 5 kg and the cart is initially at rest, its final speed is equivalent to:

9 m/s

15 m/s

20 m/s

10 m/s

Based on the given information, the cart has a mass of 5 kg and is initially at rest. The final speed of the cart can be determined using the principles of Newton's second law of motion. According to this law, the force acting on an object is equal to its mass multiplied by its acceleration. Since the cart is initially at rest, the net force acting on it is zero. Therefore, there is no acceleration and the final speed of the cart will also be zero. Hence, the correct answer is 9 m/s.

Explanation

Based on the given information, the cart has a mass of 5 kg and is initially at rest. The final speed of the cart can be determined using the principles of Newton's second law of motion. According to this law, the force acting on an object is equal to its mass multiplied by its acceleration. Since the cart is initially at rest, the net force acting on it is zero. Therefore, there is no acceleration and the final speed of the cart will also be zero. Hence, the correct answer is 9 m/s.

9. What is the average force that a gun exerts on a bullet shot with an impulse of 14,000 N.s? Assume it took 0.4 s for the bullet to leave the barrel.

5,600 N

35,000N

30,000 N

56,000N

The average force exerted on the bullet can be calculated using the formula F = Δp/Δt, where F is the force, Δp is the change in momentum, and Δt is the change in time. In this case, the impulse of 14,000 N.s is equal to the change in momentum. Given that the bullet took 0.4 s to leave the barrel, we can substitute these values into the formula to find the average force. Therefore, the average force exerted on the bullet is 14,000 N.s / 0.4 s = 35,000 N.

Explanation

The average force exerted on the bullet can be calculated using the formula F = Δp/Δt, where F is the force, Δp is the change in momentum, and Δt is the change in time. In this case, the impulse of 14,000 N.s is equal to the change in momentum. Given that the bullet took 0.4 s to leave the barrel, we can substitute these values into the formula to find the average force. Therefore, the average force exerted on the bullet is 14,000 N.s / 0.4 s = 35,000 N.

10. A blue billiard ball is moving at speed "v" towards a red ball of the same mass standing still. Assuming it is an elastic collision, after hitting the red ball, the blue one:

Bounces back.

Stops.

Moves along with the red ball at half "v".

Moves along with the red ball at "v".

In an elastic collision, both momentum and kinetic energy are conserved. Since the red ball is standing still, its initial momentum is zero. Therefore, the blue ball must also have zero final momentum after the collision in order to conserve momentum. This means that the blue ball stops moving after hitting the red ball.

Explanation

In an elastic collision, both momentum and kinetic energy are conserved. Since the red ball is standing still, its initial momentum is zero. Therefore, the blue ball must also have zero final momentum after the collision in order to conserve momentum. This means that the blue ball stops moving after hitting the red ball.