First slide
Work
Question

Velocity –time graph for a Body of mass 10kg is shown in figure.  Work done on the Body in first two seconds of the motion is 

 

Moderate
Solution

given  m = 10kg      t = 2 sec

 work done by the body against retardation force =decrease in kinetic energy of the body. 
  u   =   50m/s  at  t   =   0 sec.  
     a   =    ΔvΔt   =    500010  =   5m/s2  
       speed of the Body at  t  =  2 sec  is
    v  =   u+at      v  =  50+(5)2
                               v  =  40m/s
        using work –Energy  theory ,   W  =  ΔK.E    
         W  =   12mv2  12mu2
         W  =   12  10×4021210×502  =   4500J
 

Get Instant Solutions
When in doubt download our app. Now available Google Play Store- Doubts App
Download Now
Doubts App