Question

A car has a kinetic energy of 1.9 X 10 cubed joules. If the velocity of the car is decreased by half, what is its kinetic energy?

Answer 1

What formula do you use for kinetic energy?

Answer 2

KE = 1/2 mv squared

Answer 3

K=(1/2)*m*v^2

Answer 4

Right. Now if you cut v in half, you'd have:

\[KE _{1} = \frac{ 1 }{ 2 } m (\frac{ 1 }{2 }v)^{2}\]

Now, the ony difference is that you're squaring that 1/2 as well as the v. What fraction do you get?

Answer 5

I dont even know how to get the fraction but the multiple choice answers are
A; 2.2 X 10 squared Joules
B; 4.7 X 10 squared Joules
C; 5.2 X 10 squared Joules
D; 5.8 X 10 cubed Joules

Answer 6

What is \[\frac{ 1 }{ 2 } \times \frac{ 1 }{ 2 }\] ?

Answer 7

0.25?

Answer 8

good. multiply the original KE by .25 and choose the right answer - it's on there