Answer:
13.37 rev/min
Explanation:
acceleration due to gravity (g) = 9.8 m/s², centripetal acceleration (
) = 1.8 * g = 1.8 * 9.8 m/s² = 17.64 m/s².
r = 9 m
Centripetal acceleration (
) is given by:

The velocity (v) is given by:
v = ωr;  where ω is the angular velocity
Hence:
ω = v/r = 12.6 / 9
ω = 1.4 rad/s
ω = 2πN
N = ω/2π = 1.4 / 2π
N = 0.2228 rev/s
N = 13.37 rev/min
 
        
             
        
        
        
Explanation:
The given data is as follows.
          mass (m) = 170 kg,        Distance (s) = 9.6 m
         Height (h) = 3.3 m,         Force (F) = 1400 N
First, we will calculate the work performed by her as follows.
                 W = Fs
                     = 
                     = 13440 J
Hence, minimal work necessary to lift the refrigerator is as follows.
                U = mgh
                    = 
                    = 5497.8 J
Therefore, we can conclude that he performed 5497.8 J of work.
 
        
             
        
        
        
Answer:in X-rays 
Explanation:
Radiation are used in X-rays for the treatment of tumours, and some skin diseases,cancer cells can be destroyed by X-rays 
 
        
             
        
        
        
Answer:
Explanation:
1. Impulse, I = F.t
   The statement impulse is the product of Force and distance is false.
2. F = m g
    Force necessary to lift the object depends on the mass of the object.
    statement 2 is false.
3. Joule is equal to Newton times meter.
     Statement 3 is false.
4. Work done to lift an object is correct statement.
    Statement 4 is true.
5. Kinetic energy of an object is due to motion.
   Statement 5 is false.
6. Stopping distance is directly proportional to the square of velocity.
      If velocity is doubled, stopping distance is quadrupled.
     Statement 6 is false.
 
        
             
        
        
        
Average Velocity=Total Distance/Total Time
 
 