Answer:
The principle of conservation of energy and angular momentum 
Explanation:
At point A, the car experienced maximum of potential energy
As it moves down the hill, the potential energy decreases while the kinetic energy increases.
The maximum kinetic energy of the car is needed for the attainment of enough centripetal force to help the car move through the loop without falling .
 
        
             
        
        
        
Answer:

Explanation:
It is given that,
Mass of the grindstone, m = 3 kg
Radius of the grindstone, r = 8 cm = 0.08 m
Initial speed of the grindstone, 
Finally it shuts off, 
Time taken, t = 10 s
Let  is the angular acceleration of the grindstone. Using the formula of rotational kinematics as :
 is the angular acceleration of the grindstone. Using the formula of rotational kinematics as :



Let  is the number of revolutions of the grindstone after the power is shut off. Now using the third equation of rotational kinematics as :
 is the number of revolutions of the grindstone after the power is shut off. Now using the third equation of rotational kinematics as :





or

So, the number of revolutions of the grindstone after the power is shut off is 50.
 
        
             
        
        
        
Answer:
on an average, <em>2</em><em>0</em><em>H</em><em>z</em><em> </em><em>to</em><em> </em><em>2</em><em>0</em><em>k</em><em>H</em><em>z</em>
 
        
             
        
        
        
Answer: 5000N
Explanation:
The basic principle of a circular orbit is that Fg = m × ac, so as we have the mass and the centripetal acceleration (also called normal acceleration) we just have to operate. Fg = 1000kg × 5m/s² = 5000N