In a shotput event an athlete throws the shotput of mass 10 kg with an initial speed of 1 m/s at 45o from height 1.5 m above ground. Assuming air resistance to be negligible and acceleration due to gravity to be 10 m/s2, the kinetic energy of the shotput when it just reaches the ground will be a) 2.5 J b) 5.0 J c) 52.5 J d) 155.0 J
Correct option is D) Initial KE of the shotput =21(10 kg)(1 m/s2)=5 J Initial PE of the shotput at a height 1.5 m above ground =mgh=(10 kg)(10 m/s2)(1.5 m)=150 J Total initial energy of the shotput =155 J Since air resistance is negligible and final potential of the shotput as it hits the ground (h=0) is zero, kinetic energy of the shotput on hitting the ground =155 J.
