Speed of ball is 19.80 m/s .
<u>Explanation:</u>
We have , a 2.0 kg ball is resting at the top of a 20 m hill. if the ball rolls down the entire hill,We need to find how fast will it be going.Let's find out:
We know that,
Potential energy : This is the energy possessed by an object due to it's virtue of height and is given by , where m is mass , g is acceleration due to gravity & h is height !
Kinetic energy : This is the energy possessed by an object due to it's virtue of motion and is given by , where m is mass & v is the velocity of object !
By conservation of energy :
⇒
⇒
⇒
According to question , h=20 m i.e.
⇒
⇒
⇒
Hence , Speed of ball is 19.80 m/s .