JEE Main201910 Jan 2019Evening ShiftPhysicsWork, Power and EnergyActual
A particle which is experiencing a force, given by F → = 3 i ^ - 12 j ^ , undergoes a displacement of d → = 4 i ^ . If the particle had a kinetic energy of 3 J at the beginning of the displacement, what is its kinetic energy at the end of the displacement?
Options
- A9   J .
- B15   J .
- C12   J .
- D10   J .
Correct answer
B. 15   J .
Step-by-step solution
Work done by the force, F → . s → = 3 i ^ + 12 j ^ ⋅ 4 i ^ = 12   J By work energy theorem, W total = ∆ K 12   J = K f - K i 12 + K i = K f ∴ K f = 12 + 3 = 15   J