Question

If an object with a mass of `5 kg` changes speed from `4m/s` to `7m/s`, by how much does its kinetic energy change?

Answer 1

Change in KE`=82.5" "`joule

Explanation:

Given `v_f=7" "`m/sec and `v_0=4" "`m/sec
and mass `m=5" "`kg

Formula for Kinetic Energy :

`KE=1/2*mv^2`

Change in KE`=1/2*mv_f^2-1/2*mv_0^2`

Change in KE`=1/2*m*(v_f^2-v_0^2)`

Change in KE`=1/2*5*(7^2-4^2)`

Change in KE`=82.5" "`joule

God bless....I hope the explanation is useful.

Answer 2

`=82.5J`

Explanation:

• Mass of the object `m = 5kg`
• Initial velocity `v_i=4m/s`
• Initial velocity `v_f=7m/s`
• The change in KE =`1/2xxm(v_f^2-v_i^2)=1/2xx5xx(7^2-4^2)J`

`=82.5J`