If an object with a mass of 2 kg changes speed from 3 m/s to m/s, by how much does its kinetic energy change?

1 Answer
May 14, 2016

4J

Explanation:

Recall that the formula for kinetic energy is:

color(blue)(|bar(ul(color(white)(a/a)DeltaE_k=1/2mv^2color(white)(a/a)|)))

where:
DeltaE_k=change in kinetic energy
m=mass (kilograms)
v=velocity (metres per second)

Start by breaking down DeltaE_k into final kinetic energy minus the initial kinetic energy.

DeltaE_k=1/2mv_f^2-1/2mv_i^2

Simplify.

DeltaE_k=1/2m(v_f-v_i)^2

Substitute the given values.

DeltaE_k=1/2(2kg)(1m/s-3m/s)^2

Solve.

DeltaE_k=1/2(2kg)(4m^2/s^2)

DeltaE_k=color(green)(|bar(ul(color(white)(a/a)color(black)(4J)color(white)(a/a)|)))