Answer with explanation:
We are given that  
Mass of ball, 75 g=
75 g=
 1 kg=1000 g
Height,

Horizontal velocity,
Mass of plate
a.Initial velocity of plate,
Velocity before impact=
Where 
Velocity after impact,
According to law of conservation of momentum  

Substitute the values  



Velocity of plate=1.69 m/s
b.Initial energy=
Final energy=
Final energy=
Energy lost due to compact=Initial energy-final energy=1.326-1.162=0.164 J
 
        
             
        
        
        
Answer:
r = 20 m
Explanation:
The formula for the angular momentum of a rotating body is given as:
L = mvr
where,
L = Angular Momentum = 10000 kgm²/s
m = mass
v = speed = 2 m/s
r = radius of merry-go-round 
Therefore,
10000 kg.m²/s = mr(2 m/s)
m r = (10000 kg.m²/s)/(2 m/s)
m r = 5000 kg.m   ------------- equation 1
Now, the moment of inertia of a solid uniform disc about its axis through its center is given as:
I = (1/2) m r²
where,
I = moment of inertia = 50000 kg.m²
Therefore,
50000 kg.m² = (1/2)(m r)(r)
using equation 1, we get:
50000 kg.m² = (1/2)(5000 kg.m)(r)
(50000 kg.m²)/(2500 kg.m) = r
<u>r = 20 m</u>
 
        
             
        
        
        
Memorize this and you'll be able to do ALL of these:  <em>1  kg = 1,000 g</em>
So if you have some grams, divide the number by 1,000 to get kilograms.
1,000 g = 1.000 kg 
500 g = 0.500 kg 
100 g = 0.100 kg 
50 g = 0.050 kg 
20 g = 0.020 kg 
10 g = 0.010 kg
        
             
        
        
        
C.Perform push ups and curl-ups daily