AP EAMCET202018 Sep 2020Evening ShiftPhysicsWork, Power and EnergyActual
A machine which is (70 % ) efficient raises a (10 ~kg ) body through a certain distance and spends (100 ~J ) energy. The body is then released. On reaching the ground, the kinetic energy of the body will be
Options
- A0
- B(70 ~J )
- C(50 ~J )
- D(35 ~J )
Correct answer
B. (70 ~J )
Step-by-step solution
Energy spent by the machine to raise the body of mass (10 ~kg ) at certain height, is (E=100 ~J ) Since, machine is only (70 % ) efficient. Hence, energy used by machine, ( aligned E^ & =70 % of E & = 70 100 100=70 ~J aligned ) When body is released, then whole energy spent by machine is converted into kinetic energy on reaching the ground. ( ) Kinetic energy, (K=E^ =70 ~J )