Assignment: Momentum and Collision Math
1. While skiing, Sam flies down a hill and hits a jump. He has a mass of 75 kg, and he leaves the
jump at 18 m/s. What is his momentum as he leaves the jump?
p= momentum
mass=m= 75 kg
velocity=v=18
p=mv
p=75(18)= 1350kg-m/s
2.
How fast would a 0.25 kg football have to be traveling to have the same momentum as a 0.05 kg
bullet travelling 500 m/s?
We have to solve the equation by the momentum of these two objects:
0.25 v=0.05(500)
v=100m/s
3. Sarah, who has a mass of 55 kg, is riding in a car at 20 m/s. She sees a cat crossing the street
and slams on the brakes! Her seatbelt stops her from flying forward, bringing her to rest in 0.5
seconds. How much force did the seatbelt put on Sarah?
We have to use the formula delmv=fdelt so therefore we get this solution: 55(20) =F(0.5)
F=2200 N
4. A big league hitter attacks a fastball! The ball has a mass of 0.16 kg. It is pitched at 38 m/s. After
the player hits the ball, it is now traveling 44 m/s in the opposite direction. The impact lasted
0.002 seconds. How big of a force did the ballplayer put on that ball?
In order to solve this equation we will have to use two formulas:
p=m(v)
I = del(p)= f(t)
Then:
p= m(v)=o.16kg(-38m/s) =-6.08N(s)
p=m(v)=0.16kg(44m/s) =+ 7.04 N(s)
del(p)=+7.04n(s)-(-6.08Ntime(s) ) =13.12 N(s)
I= del(p)=f(t)=>f=del(p)(t)= 13.12N(s)/o.oo2 s=6,560 N
Therefore the answer is 6,560 N
5. Someone fires a 0.04 kg bullet at a block of wood that has a mass of 0.5 kg. (The block of wood
is sitting on a frictionless surface, so it moves freely when the bullet hits it). The wood block is
initially at rest. The bullet is traveling 300 m/s when it hits the wood block and sticks inside it. Now
the bullet and the wood block move together as one object. How fast are they traveling?
The momentum of the wood and the bullet is equal to the bullet before it hits the actual wood so
therefore:
6. 0.04(300) =120kg m/s
Therefore (0.5+0.04)(v)= 120kg m/s/ 0.54kg=222.2 m/s
7. Two kids are roller skating. Amy, with a mass of 55 kg, is traveling forward at 3 m/s. Jenny, who
has a mass of 40 kg, is traveling in the opposite direction at 5 m/s. They crash into each other
and hold onto each other so that they move as one mass. How fast are they traveling?
They are traveling at 8m/s.
8. Jake is bowling with a 8 kg bowling ball. He rolls the ball at 7 m/s, and it hits one stationary pin
with a mass of 2 kg. The pin goes flying forward at 12 m/s. How fast is the bowling ball now
traveling?
8kg(7m/s)=56kg m/s The momentum of the pin after getting hit is 24 km m/s so after hitting the
pin the momentum is 56 kg m/s
9. John has to hit a bottle with a ball to win a prize. He throws a 0.4 kg ball with a velocity of 18 m/s.
It hits a 0.2 kg bottle, and the bottle flies forward at 25 m/s. How fast is the ball traveling after
hitting the bottle?
The momentum of the bottle is 0.4(18)=7.2kg m/s , therefore the momentum of the bottle after
being hit is 0.2(25)= 5kg m/s , therefore once again we have to calculate the speed so: 2.2/0.4=
5.5m/s