Question

A car has a kinetic energy of 1.9 × 103 joules. If the velocity of the car is decreased by half, what is its kinetic energy? 2.2 × 102 joules 4.7 × 102 joules 5.2 × 102 joules 5.8 × 103 joules

Answer 1

If the velocity is decreased by half, then Kinetic energy will reduced to it's 4 times,
= 1.9 * 10³ / 4
=  4.75 * 10²

In short, Your Answer would be Option B

Hope this helps!

Answer 2

Answer:

4.7 x 10^2 Joule

Explanation:

The energy possessed by the motion of body is called its kinetic energy.

The formula for the kinetic energy of a body is given by

K.E = \frac{1}{2}mv^{2}    

The kinetic energy is directly proportional to the square of velocity and the mass of body.

$K_{1} = \frac{1}{2}mv^{2}$   ..... (1)

$K_{2} = \frac{1}{2}m\left ( \frac{v}{2} \right )^{2}$ ..... (2)

Dividing equation ((2) by equation (1), we get

$K_{2} = \frac{K_{1}}{4}$

$K_{2} = \frac{1.9 \times 10^{3}}{4}$

K2 = 4.7 x 10^2 Joule