1. A 3.0-kg object moves to the right at 4.0 m/s. It collides in a perfectly ine
ID: 1571171 • Letter: 1
Question
1. A 3.0-kg object moves to the right at 4.0 m/s. It collides in a perfectly inelastic collision with a 6.0 kg object moving to the left at 2.0 m/s. What is the total kinetic energy after the collision?
A) 24 J
B) 72 J
C) 0 J
D) 36 J
2. Consider three drinking glasses. All three have the same area base, and all three are filled to the same depth with water. Glass A is cylindrical. Glass B is wider at the top than at the bottom, and so holds more water than A. Glass C is narrower at the top than at the bottom, and so holds less water than A. Which glass has the greatest liquid pressure at the bottom?
A) Glass A
B) Glass B
C) Glass C
D) All three have equal pressure.
3. A crate and a ball of equal mass are placed at the same height on an inclined plane and released from rest simultaneously. The crate slides down without friction, and the ball rolls down without slipping. Which has the most total kinetic energy (KE) at the bottom of the ramp?
A) crate
B) ball
C) both have zero KE at the bottom
D) both have the same non-zero KE
4. On a winter night you go to the bathroom in your heated house, which you have kept at the same temperature for several hours. Which of these items on the bathroom floor is at the highest temperature?
A) the rug
B) the floor tile
C) both are the same temperature
D) not enough info to say
Explanation / Answer
1.
Inelastic means they stick together
Intial momentum = Final momentum
m1*v1i + m2*v2i = (m1+m2)*vf
vf = (m1*v1i + m2*v2i)/(m1+m2)
To the right is positive
vf = (3*4 - 2*6) / (3+6) = 0
Since they are not moving, the kinetic energy = 0 J
2.
Correct answer is (D)
all three have equal pressure