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

Answer:

#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)|)))#