Answer:
4
Explanation:
As you can see in the free body diagram there are 4 forces acting on the body.
 
        
             
        
        
        
Answer:
light waves can travel in vacuum but sound waves require a medium to travel 
also light waves are electromagnetic waves while sound waves are mechanical, light waves are transverse waves while sound waves are longitudinal waves
 
        
             
        
        
        
Final speed after collision with the wall

before collision the speed of ball initially

time taken for the collision

now as per the formula of acceleration we know that

now plug in all values in it


so acceleration is - 5 m/s/s for above situation
 
        
             
        
        
        
The awnser would be True. Hope I helped!