Question

2. An explosion of gas from a Hawaiian volcano blows a rock into the sky. The rock has 2000J of kinetic energy. Find mass if the rock had a velocity of 20m/s?

Answer 1

Answer:

ke =2000j

ke=1/2×mass×[velocity]^2

2000j=1/2×X×400

=20 kg

Answer 2

Answer:

Mass of the rock is 10kg

Explanation:

Given the kinetic energy of rock, $KE=2000J$

          velocity,  $v= 20m/s$

Kinetic energy of a body of mass m is given by

                     $KE=\frac{1}{2} mv^{2}$

             $\implies 2000=\frac{1}{2} \times m \times (20)^{2}$

                 $\implies m=\frac{2000}{200}=10kg$

Hence, mass of the rock is 10kg.