A 12.5-kg crate slides along a horizontal frictionless surface at a constant speed of 4.0 m/s. The crate then slides down a frictionless incline and across a second horizontal surface as shown in the figure.
-What is the kinetic energy of the crate as it slides on the upper surface?
A)30 J
B)80 J
C)100 J
D)200 J
E)490 J

Question

A 12.5-kg crate slides along a horizontal frictionless surface at a constant speed of 4.0 m/s. The crate then slides down a frictionless incline and across a second horizontal surface as shown in the figure. 
-What is the kinetic energy of the crate as it slides on the upper surface?
A)30 J 
B)80 J 
C)100 J 
D)200 J 
E)490 J

Quizplus · Accepted Answer

Since the surface is frictionless, the kinetic energy of the crate is conserved throughout its entire path. Thus, the kinetic energy of the crate on the upper surface is equal to its kinetic energy just before it reached the incline. The kinetic energy of the crate can be calculated using the formula:

Kinetic energy = (1/2) * mass * velocity^2

K = (1/2) * 12.5 kg * (4.0 m/s)^2
K = 100 J

Therefore, the correct answer is C) 100 J.

A 125-Kg Crate Slides Along a Horizontal Frictionless Surface at a a Constant