1. One truck is heading east at 80 miles per hour. Its mass is 3000 kg. A car (m
ID: 2141224 • Letter: 1
Question
1. One truck is heading east at 80 miles per hour. Its mass is 3000 kg. A car (m=1000 kg) is heading north at 40 miles per hour. They collide and stick together. How much energy is lost in the collision? What is the velocity and direction of the car/truck?
2. From the shore of a frozen lake, Eli Manning throws a 2 kg football at a velocity of 20 m/s. A person (m=30 kg) standing on the ice ( (mu_{k}=0.02) ) catches the ball. What is their velocity immediately after they catch it? How far do they slide before they come to a stop?
3. One fires a bullet (m=50kg) at a block of wood (m=2kg) resting on a frictionless surface. The initial velocity of the bullet is 400 m/s. After passing through the block, its velocity is 100 m/s. What is the velocity of the block? How much energy is lost?
4. A particle of 8 kg with a velocity 40 m/s hits a 40 kg particle that is at rest. The collision is elastic. What are the final velocities of the particles?
5. A particle of 8 kg with a velocity of 40 m/s at 0 degrees hits another particle of 25 kg that is moving at a velocity of 70 m/s at 90 degrees. The collision is elastic. What are the velocities and directions of the particles after the collision?
Explanation / Answer
1) U1 = 80*1.6*5/18 = 35.36 m/s
U2 = 40*1.6*5/18 = 17.68 m/s
m1 = 3000kg, m2 = 1000kg
let theta is the angle made by the cars after the collision
with east
in x direction
m1*u1 = (m1+m2)*v*cos(theta)
106666.67 = (3000+1000)*v*cos(theta)
V*cos(theta) = 20.67 --(1)
in y direction
m2*u2 = (m1+m2)*v*sin(theta)
17680 = (3000+1000)*v*sin(theta)
v*sin(theta) = 4.42 --(2)
(2)/(1) = sin(theta) = 0.2138
theta = 12.35 degrees
V = 4.42/sin(12.32) = 20.62 m/s
2)
2*20 = (2+30)*v
v = 1.25 m/s
3)
i think m = 50 g = 0.05kg
0.05*400 = 0.05*100 + 2*v
v = 7.5 m/s
KEf - KEi = 3693.75 J
4)
v1 = (8-40)*40/(8+40) = -26.67 m/s
v2 = m1*u1/(m1+m2) = 6.67 m/s
5) this similar to the first problem....
change the values
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