Balance and beaker of water. The balance will measure mass and the beaker will measure the volume when you take the initial volume without the key subtracting that value from the value with the key in the beaker
        
                    
             
        
        
        
Answer:
-v/2
Explanation:
Given that:
- Collides with the wall going through a sliding motion on on the plane smooth surface.
- Upon rebounding from the wall its kinetic energy becomes one-fourth of the initial kinetic energy before collision.
<u>We know, kinetic energy is given as:</u>

consider this to be the initial kinetic energy of the body.
<u>Now after collision:</u>


Considering that the mass of the body remains constant before and after collision.

Therefore the velocity of the body after collision will become half of the initial velocity but its direction is also reversed which can be denoted by a negative sign.
 
        
             
        
        
        
D because u r using your energy to do all the things
 
        
                    
             
        
        
        
Explanation:
The centripetal force acting on a particle is given by :

Since,  
 


Case 1.
If 
Since, 
So, 

So, the force becomes,

F is independent of r
Case 2.
If 


So, 
So, the force is inversely proportional to the square of radius.
Case 3.
If T is independent of r, the force will be directly proportional to the radius of orbit.
Hence, this is the required solution.