Answer:
The percentage of its mechanical energy does the ball lose with each bounce is 23 % 
Explanation:
Given data,
The tennis ball is released from the height, h = 4 m
After the third bounce it reaches height, h' = 183 cm
                                                                        = 1.83 m
The total mechanical energy of the ball is equal to its maximum P.E
                                       E = mgh
                                           = 4 mg
At height h', the P.E becomes
                                       E' = mgh'
                                            = 1.83 mg
The percentage of change in energy the ball retains to its original energy, 
                                  
 
                                   ΔE % = 45 %
The ball retains only the 45% of its original energy after 3 bounces.
Therefore, the energy retains in each bounce is
                                    ∛ (0.45) = 0.77
The ball retains only the 77% of its original energy.
The energy lost to the floor is,
                                 E = 100 - 77
                                    = 23 %
Hence, the percentage of its mechanical energy does the ball lose with each bounce is 23 %       
 
        
             
        
        
        
Answer:
2090 J
Explanation:
the work done to move the cart is equal to the product between the force applied and the distance traveled:

In this case, the force applied is F=209 N, while the distance covered is d=10 m, therefore the work done is

 
        
                    
             
        
        
        
Answer:
The duration of the movie is longer than 2 hrs.
Explanation:
Given:
The duration of the movie observed by the crew on the spacecraft is 2 hrs.
According to time-dilation formula:

Here, 
 is the required time, 
 is the original time, 
 is the velocity of the spacecraft and 
 is the velocity of light.
Since 
, so 
.
So the time required will be large.
 
        
             
        
        
        
Answer:
The speed of the car when load is dropped in it is 17.19 m/s.
Explanation:
It is given that,
Mass of the railroad car, m₁ = 16000 kg
Speed of the railroad car, v₁ = 23 m/s
Mass of additional load, m₂ = 5400 kg
The additional load is dropped onto the car. Let v will be its speed. On applying the conservation of momentum as :



v = 17.19 m/s
So, the speed of the car when load is dropped in it is 17.19 m/s. Hence, this is the required solution.