Question

A truck pushes a pile of dirt horizontally on a frictionless road with a net force of
20

N
20N20, start text, N, end text for
15.0

m
15.0m15, point, 0, start text, m, end text.
How much kinetic energy does the dirt gain?

Answer 1

Answer:

300 Joules

Explanation:

This is a common question on Khan Academy's "Calculating change in kinetic energy from a force" practice exercises. (AP Physics 1)

• The simplest method to use is the following: $W = F * d * cos(theta)$, where W represents work (joules), F represents force (newtons), d represents distance (meters), and theta represents the angle of the force that's being applied.
• In this scenario, the force being applied is horizontal, so we can remove the $cos(theta)$ from our equation.
• So, our equation is now: $W = F * d$. This would mean that $W = 20 * 15$, which is equal to $300$.
• Our answer is 300 joules. (this value is positive and not negative because kinetic energy is being GAINED, not LOST)

Here's the real question without all the formatting:

• A truck pushes a pile of dirt horizontally on a frictionless road with a net force of 20 N for 15.0 m. How much kinetic energy does the dirt gain?