A rubber ball bounces off of a wall with an initial speed v and reverses its direction so its speed is v right after the bounce. As a result of this bounce, which of the following quantities of the ball are conserved?
A) the kinetic energy of the ball
B) the momentum of the ball
C) both the momentum and the kinetic energy of the ball
D) None of the above quantities are conserved.

Explanation:

Given that,

The rubber ball hits the wall and bounce off in opposite direction.

This type of collision is called elastic collision, when two bodies collide, the relative velocity of the two bodies is unchanged in magnitude but reversed in direction

Thus, in such an elastic collision both the momentum and the kinetic energy are conserved

The correct answer is

C) both the momentum and the kinetic energy of the ball.l

beta is electron from nucleus

something from nucleus has changed, but charge must be same for cons of charge

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =