m = mass of the object moving = ?
v = speed of the object moving = 18 m/sec
K = kinetic energy of the object moving = 140 J
Kinetic energy of an object is given as
K = (0.5) m v²
where m = mass of object , v = speed of object , K = kinetic energy of object
hence for object , kinetic energy is given as
K = (0.5) m v²
inserting the values
140 = (0.5) m (18)²
140 = 162 m
m = 140/162
m = 0.86 kg
hence mass of the object comes out to be 0.86 kg