This includes answers to the following QUICK CHECKs for Physical Science: Momentum, The Moment of Impact, Using Vectors to Describe Momentum, and Zero Net Force. They are all 100% accurate, enjoy!
MOMENTUM QUICK CHECK
A billiard ball moves with 3 kg⋅m/s of momentum and strikes three other billiard balls. What is the total momentum of the balls after the collision?
ANSWER- 3 kg⋅m/s
A small rock bounces off the windshield of a moving car and experiences a large change in velocity. How does the car’s momentum change?
ANSWER- It has a change in momentum equal to that of the rock, in the opposite direction.
An object has a mass of 5 kg and a velocity of 20 m/s. What is the momentum of the object?
ANSWER- 100 kg⋅m/s
Which of Newton’s laws of motion states that an object at rest stays at rest and an object in motion stays in motion with the same speed and the same direction unless acted upon by an unbalanced force?
ANSWER- Newton's first law of motion
Which is always true in a closed system?
ANSWER- Momentum is conserved.
THE MOMENT OF IMPACT QUICK CHECK
Which mathematical representation correctly identifies impulse?
ANSWER- impulse= force x time
In a closed system, a ball with a mass of 3 kg and a momentum of 24 kg·m/s collides into a ball with a mass of 1 kg that is originally at rest. Which statement describes the momentum of the balls and the total momentum?
ANSWER- The momentum of each ball changes, and the total momentum stays the same.
In a closed system, three objects have the following momentums: 110 kg⋅m/s, −65 kg⋅m/s, and −100 kg⋅m/s. The objects collide and move together. What is the total momentum after the collision?
ANSWER -55 kg·m/s
In a closed system, an object with a mass of 1.5 kg collides with a second object. The two objects then move together at a velocity of 50 m/s. The total momentum of the system is 250 kg⋅m/s. What is the mass of the second object?
ANSWER- 3.5 kg
A cue stick has a mass of 0.5 kg. The cue stick hits a ball with a mass of 0.2 kg at a velocity of 2.5 m/s. What is the velocity of the ball after it is hit?
ANSWER- 6.3 m/s
USING VECTORS TO DESCRIBE MOMENTUM QUICK CHECK
Which of these quantities is a vector?
ANSWER- momentum
What is the representation of the momentum vector?
ANSWER- an arrow
What is the formula for the momentum p?
ANSWER- p=m⋅v
What happens to the total momentum in a system of two interacting objects when a net force is exerted upon the system?
ANSWER- The total momentum is conserved.
What is the magnitude momentum of a 2 kg body that moves with a speed of 3 m/s?
ANSWER- 6.0
ZERO NET FORCE QUICK CHECK
How can the momentum of a moving object be found?
ANSWER- by multiplying its mass by its velocity
In everyday life, changing the speed of a moving object will change all but which value?
ANSWER- mass
What does Newton's second law of motion state?
ANSWER- Force equals mass times acceleration.
If the total net force on a system is zero, assuming the mass remains constant, which must be true?
ANSWER- The acceleration is zero.
Which scenario describes an object experiencing zero net force?
ANSWER- A balloon floating upward at a constant velocity.
What does Newton's second law of motion state?
ANSWER- Force equals mass times acceleration.
Well yes, but a better way to say it, and the way Newton expressed it, is:
Net force = rate of change of momentum
if the mass is constant that is m a but if the mass changes (like near the speed of light) it is d/dt (m v).
I notice your next question mentions " ..... assuming the mass remains constant, ......"
What happens to the total momentum in a system of two interacting objects when a net force is exerted upon the system?
ANSWER- The total momentum is conserved.
HUH ???
net force ---> change of momentum