The acceleration due to gravity serves as the centripetal acceleration of the objects that orbits the Earth. The centripetal acceleration due to gravity is calculated through the equation,
a = v²/r
where v is the speed and r is the radius. Substituting the known values to the equation,
9.8 m/s² = (420 m/s)² / r
The value of r from the equation is 18000 m or equal to 18 km.
<em>Answer: 18 km</em>
Answer:Racquet force is twice of Player force
Explanation:
Given
ball arrives at a speed of 
ball returned with speed of 
average Force imparted by racquet on the ball is given by

where 
time of contact of ball with racquet


When it land on the player hand its final velocity becomes zero and time of contact is same as of racquet


From 1 and 2 we get

Hence the magnitude of Force by racquet is twice the Force by player
Answer:
first blank is chemical second blank is kinetic energy