A tennis player serves a tennis ball such that it is moving horizontally when it leaves the racquet. When the ball travels a horizontal distance of 17 m, it has dropped 55 cm from its original height when it left the racquet. What was the initial speed, in m/s, of the tennis ball

The value is

Explanation:

From the question we are told that

    The  horizontal distance traveled is  

    The decrease in height is  

Considering the vertical velocity

Generally from kinematic equation we have that

Here the initial vertical ( )  velocity is  zero

=>  

=>  

Generally the time to drop to this height is mathematically represented as

=>  

=>  

Generally given that time taken to drop to the obtained height is equal to the time taken to reach the horizontal distance , then

Here is the initial horizontal velocity

=>

unable to answer the rest since your question is incomplete

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.