Answer :
Let the mass be m
v = 5m/s
K.E = 25 J
K.E = 1/2 mv^2
25 = 1/2 m (5)^2
25 x 2 = 25m
m = 2 kg
Now if the velocity becomes 3 times then the velocity is 3 x 5 = 15m/S
Now new K.E = 1/2 x 2 x 15^2
= 225 J
v = 5m/s
K.E = 25 J
K.E = 1/2 mv^2
25 = 1/2 m (5)^2
25 x 2 = 25m
m = 2 kg
Now if the velocity becomes 3 times then the velocity is 3 x 5 = 15m/S
Now new K.E = 1/2 x 2 x 15^2
= 225 J