Question

A bicyclist goes from a speed of 5 m/s to a speed of 10 m/s. What happens to her kinetic energy?

A. Since her speed doubled, her kinetic energy is cut in half.
B. Since her speed doubled, her kinetic energy doubled.
C. Since her speed doubled, her kinetic energy increased by a factor of 4
D. Her kinetic energy did not change due to a change in speed.

Answer 1

C

Step-by-step explanation:

The kinetic energy of an object can be calculated via the following equation:

`k = (1)/(2) m {u}^(2)`

where:

K : kinetic energy

m: mass of the object

v: its velocity

when the speed changes, the kinetic energy changes as well. Lets suppose that it doubles, as on the problem stated. Then K is increased by a factor of four. in other words...

`newk = (1)/(2) m {(newu)}^(2) = (1)/(2) m {(2u)}^(2) \\ = (1)/(2) m(4 {u}^(2) ) = 4( (1)/(2) m {u}^(2) ) = 4k`