Definitions
The momentum of an object depends on _____ and _____.
Which collisions are kinetic energy lost in?
Inelastic and perfectly inelastic collisions
What is the momentum equation?
p=mv
How do you determine whether it is an elastic and inelastic collision by finding kinetic energy?
If the kinetic energy before is equal to the kinetic energy after, it is elastic. If it is not equal, it is inelastic.
What is the momentum of a 1225 kg car traveling at 45 km/h?
15,300 kg*m/s
What is impulse?
Impulse is equal to the net force on the object times the time period over which this force is applied.
Explain explosive collisions.
Objects start together and move apart at their velocities
If a ball hit a wall and stopped immediately, what would be its final velocity (Vf)?
0 m/s
A rocket explodes into two fragments, one 25 times heavier than the other. The magnitude of the momentum change of the lighter fragment is
A) 25 times as great as the momentum change of the heavier fragment.
B) 1/25 as great as the momentum change of the heavier fragment.
C) 5 times as great as the momentum change of the heavier fragment.
D) The same as the momentum change of the heavier fragment.
A 0.5 kg football is thrown with a velocity of 15m/s to the right. A stationary receiver catches the ball and brings it to rest in .02 sec. What is the force exerted on the receiver?
375N
What does safety equipment do?
It extends the stopping time, therefore decreasing the force experienced by the object
A car is traveling on a highway and a ladybug hits the front window of the car. Which experiences a greater change in momentum?
Both are the same because of Newton's third law.
What equation is used to find impulse?
J=mΔv
If you want to double the momentum of a gas molecule, by what factor must you increase its kinetic energy?
On a snow covered road, a car with a mass of 1100 kg collides head on with a van having a mass of 2500 kg traveling 8 m/s. As a result of the collision, the vehicles lock together and immediately come to rest. Calculate the speed of the car immediately before the collision.
18.2 m/s
What is the difference between momentum and kinetic energy?
Momentum is a vector quantity, which has both magnitude and direction. Kinetic energy is a scalar quantity, which does not have direction.
A car is traveling on a highway and a ladybug hits the front window of the car. Which experiences a greater acceleration?
The ladybug
How would you find force (F) if given velocity, mass and time?
mΔv=Ft
F=mΔv/t
An open freight car rolls friction-free along a horizontal track in vertically pouring rain. As water accumulates in the car, its speed...
Decreases
A 6.2 kg object heading north at 3 m/s collides with an 8 kg object heading west at 3.5 m/s. If these two masses stick together upon collision, what is their velocity after collision?
2.4 m/s 56 degrees W of N
Inertia is the resistance of any physical object to any change in its velocity.
When is there a time where momentum is NOT conserved in a collision?
Momentum is always conserved in a closed system, but in certain cases, is not always conserved in an open system.
How do you solve collisions in 2-D?
By resolving the x and y forces using trig. Make sure to include direction as well.
Three cars, car X, car Y, and car Z, begin accelerating from rest at the same time. Car X is bigger than car Y, which is bigger than car Z. The net accelerating force exerted on each car is the same. After 10 seconds, which car has the most amount of momentum?
They all have the same momentum.
A 15 kg penguin waddling east at a velocity of 7 m/s collides with a stationary 10 kg penguin. After the collision, the 15 kg penguin is traveling at a velocity of 4.2 m/s 20 degrees S of E. What is the velocity of the 10 kg penguin after the collision?
5.1 m/s 25 degrees N of E