A moving object has a kinetic energy of 141 J and a momentum with magnitude of 30.2 kg·m/s.

Question

(a) Determine the mass of the object.

(b) Determine the speed of the object.

Answer 1

Kinetic energy (E_K) can be calculated from the equation:

E_K = (1/2)mv² so 141 = (1/2)mv² or mv² = 282

Momentum (P) can be calculated from the equation:

P = mv so 30.2 = mv or m = 30.2/v

So, utilizing m = 30.2/v and plugging "30.2/v" into the other equation in place of "m" we get:

mv² = 282

(30.2/v)v² = 282

30.2v = 282

v = 282/30.2 = 9.38 m/s

Since m = 30.2/v then m = 30.2/9.38 = 3.23 kg