Question

When a cars speed doubles, what happens to its kinetic energy?

• A. It is quartered
• B. It is halved
• C. It is unchanged
• D. It is doubled
• E. It is quadrupled

Answer 1

The correct option is E It is quadrupled

Initial kinetic energy $K=\frac{1}{2}m{v}^2$

New speed of the car $v^{\prime }=2v$

Thus new kinetic energy $K^{\prime }=\frac{1}{2}m(v^{\prime }{)}^2=\frac{1}{2}m(2v{)}^2=4K$

Thus kinetic energy is quadrupled.