An object moving with a speed of 21 m/s and has a kinetic energy of 140 J, what is the mass of the object.

0.635 kg

Explanation:

Recall that Kinetic energy is defined as:

K. E. = (1/2) mv²,

where

K. E = Kinetic energy = given as 140J

m = mass (we are asked to find this)

v = velocity = given as 21 m/s

Substituting the above values into the equation:

K. E. = (1/2) mv²

140 = (1/2) m (21) ² (rearranging)

m = (140) (2) / (21) ²

m = 0.635 kg

Answer:2940