Momentum
What is the formula for momentum?
p=mv
What is the formula for impulse?
J=F (change in) t
What is the difference between the 3 types of collisions?
Momentum and KE conserved-elastic. Momentum but not KE conserved-inelastic. Perfectly inelastic-max KE is lost, objects stick together.
In an isolated system if there are no nonconservative forces, what can we say about Energy and Momentum?
Both conserved
What is the formula for change in momentum?
p=m(change in) v
Describe the relationship between momentum and impulse
change in momentum equals impulse
A 70-kg student stands at rest on frictionless ice holding a 5-kg bowling ball. They throw the ball forward at 8 m/s.
What is the student’s recoil velocity?
- 0.57 m/s
If both the mass and the velocity of a ball were doubled, the kinetic energy of the ball would increase by a factor of
8
A cart with a large mass and a cart with a small mass roll at the same speed. Which cart has more momentum?
Large mass
Which has the greatest impulse? A large force over a short time or a large force over a long time?
A large force over a long time
A 0.50-kg cart moving at 3.0 m/s collides elastically with a 1.00-kg cart initially at rest. The 0.50 kg cart moves with a final velocity of 1.0 m/s. What is the final velocity of the 1.00 kg cart?
1.0 m/s
A 0.20 kg pendulum is released from a height of 0.30 m. What is its speed at the lowest point?
2.42 m/s
A 2 kg toy car is moving 2.5 m/s. What is the momentum?
5 kgm/s
Why is the risk of injury less when a car crashes into a crash cushion?
Extends the time of the collision so the force is less.
A 1200-kg car is traveling east at 22 m/s when it rear-ends a 900-kg car moving east at 15 m/s. The cars lock together after impact.
What is their combined velocity immediately after the collision?
19 m/s
A 0.14 kg baseball moving at 42 m/s rebounds at 39 m/s in the opposite direction in 0.02 s. Find the average force.
567 N
A .25 kg dart initially moving 5 m/s hits a dart board and bounces off at 2 m/s. What is the change in momentum?
-1.75 kgm/s
A kid sledding down a hill hits a snow pile with 10 N of force in .032 seconds. What is the impulse?
0.32 Ns
What is the final kinetic energy of the system if 2 pizza doughs, each of mass .5 kg, collide and have a resultant velocity of 1.5 m/s?
1.125 J
A North-going Zak has a mass of 50 kg and is traveling at 4 m/s. A South -going Zak has a mass of 40 kg and is traveling at 5 m/s. If they have a perfectly inelastic collision, what is their final velocity? What are the initial and final total kinetic energies?
0 m/s, 900 J, 0 J