1.
Momentum means or is most associated with:
Correct Answer
C. Inertia in Motion
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.
2.
What could be the momentum of a 1,300-kg car that moves at 4 m/s?
Correct Answer
B. 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.
Will a large truck always have more momentum than a roller skate?
Correct Answer
A. No, a large truck at rest has no momentum. A moving roller skate has momentum.
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.
4.
Why is falling on a floor with more give less dangerous than falling on a floor with less give?
Correct Answer
A. 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.
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.
5.
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?
Correct Answer
D. Law of Conservation of Momentum
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.
6.
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?
Correct Answer
B. Yes, because no acceleration means that no change occurs in velocity or in momentum.
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.
7.
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:
Correct Answer
B. Stops.
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.
8.
What impulse occurs when an average force of 15 N is exerted on a cart for 3.0 s?
Correct Answer
C. 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.
9.
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:
Correct Answer
A. 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.
10.
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.
Correct Answer
B. 35,000N
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.