Question

a 10 kg rock falls from a 20 m cliff. What is kinetic and potential energy when the rock has fallen 10m?​

Answer 1

Answer:

980 J

Explanation:

mass of the rock=10kg

the distance traveled by the rock from the fall to the point of interest=10m

Kinetic energy=(1/2)*m*v^2

Need to determine the value of v^2

Use equation of motion

=> V^2-U^2=2as

U=0

so, V^2=2as

=>V^2=2*9.8*10 (g taken as 9.8 m/s^2)

=>V^2=196m^2/s^2

now plug this value into KE equation

so KE=(1/2)*10*196

=>KE=980 J

Answer 2

Answer:

Potential energy is equal to mgh

Explanation:

U = mgh

U = 10×9.8×20

U = 1960

Kinetic energy = 1/2 × 10 × √392

= 140