Question

A horizontal force of 200 n is applied to move a 55-kg cart (initially at rest) across a 10-m level surface. what is the final kinetic energy of the cart?

Answer 1

Kinetic energy is the energy that is possessed by an object that is moving. It is calculated by one-half the product of the mass and the square of the velocity of the object. We need to determine the velocity of the cart that is moving. 

First, we use Newton's Second Law of motion;
Force = ma 
200 = 55a 
a = 3.64 m/s^2 

Then, from the kinematic equation we calculate the velocity;
v^2 = v0^2 + 2ax

where v is the final velocity, v0 is the initial veocity (zero since it initially start at zero), a is the acceleration ( 3.64 m/s^2) and x is the distance traveled.

v^2 = 0^2 + 2 (3.64) (10) 
v^2 = 72.73 m^2 / s^2
v = 8.53 m / s 

KE = mv^2 / 2
KE = 1/2 (55) (8.53^2) 
KE= 2000 J