Momentum Basics
The equation for linear momentum.
What is p=mvp = mvp=mv?
What is the equation for impulse?
J=FΔt or J=ΔpJ = \Delta pJ=Δp
Momentum is conserved in what type of system?
An isolated system
The center of mass of a uniform object is located where?
At its geometric center
The recoil of a gun follows what physics principle?
Conservation of momentum
SI unit of momentum
What is kg·m/s?
Increasing what quantity in a collision reduces force?
Time
What equation represents conservation of momentum?
m1v1+m2v2=m1v1′+m2v2′
This rule determines how systems move when external forces act.
Newton’s Second Law for the system
A rocket moves by expelling gas in the opposite direction. What law explains this?
Newton’s Third Law
A 2 kg object moving at 4 m/s has this momentum.
What is 8 kg·m/s?
A force of 10 N acts for 2 seconds. What is the impulse delivered?
20 Ns
What type of collision occurs when two objects collide and stick together?
Perfectly inelastic
Two objects of different masses are connected. The center of mass is closer to what?
The more massive object
A person catching a fast baseball moves their hand backward. Why?
To increase time and reduce force
If an object's velocity doubles, its momentum changes by this factor
What is 2?
How do airbags protect passengers in a collision?
By increasing the time of impact
Two skaters push off each other. What happens to their total momentum before and after?
It remains the same (zero if initially at rest)
A system has zero net external force. What happens to its center of mass?
It remains constant
In a car crash, crumple zones help by doing what?
Increasing the time of impact
A 5 kg object has 20 kg·m/s of momentum. Find its velocity.
What is 4 m/s?
A 1,000 kg car moving at 20 m/s comes to rest in 4 seconds. What is the average force exerted?
-5000 N
A 3 kg object moving at 5 m/s collides with a stationary 2 kg object. They stick together. What is the final velocity?
3 m/s
A 3 kg object at x = 2 m and a 6 kg object at x = 8 m have their center of mass at what location?
6 m
Why does a faster-moving truck have more damage potential than a slow one?
Because momentum depends on velocity