Question

A car moving with a velocity of 20 meters/second has
1.8 * 105 joules of kinetic energy. What is the mass of the car?

Answer 1

Kinetic energy is the product of mass and the square of the velocity of the moving object. In this case, we substitute the given data, that is 1.8 x10^5 joules = m * (20 m/s2)^2. Extracting the mass, the mass of the car therefore is equal to 450 kg

Answer 2

Explanation :

Given that,

Velocity of the car, v = 20 m/s

Kinetic energy of the car, $E_k=1.8\times 10^5\ J$

Kinetic energy is given by :

$E_k=\dfrac{1}{2}mv^2$

$m=\dfrac{2E_k}{v^2}$

So, $m=\dfrac{2\times 1.8\times 10^5\ J }{(20\ m/s)^2}$

m = 900 kg

Hence, the mass of the car is 900 kg