2022 · Q45
Two objects, x and y, have equal mass and are moving with speeds u and 3u respectively. Their kinetic energies are related as
general-sciencephysics-mechanics
- Akx = ky
- B2kx = ky
- C9kx = ky
- D3kx = ky
Explanation
Kinetic energy is (1/2)mv². With equal masses m, kx = (1/2)mu² and ky = (1/2)m(3u)² = (1/2)m·9u² = 9·(1/2)mu² = 9kx. So ky = 9kx, i.e., 9kx = ky. The tripling of speed increases kinetic energy ninefold since KE scales with the square of velocity. Hence option C.