Q.

A particle of mass 10 g moves along a circle of radius 6.4 cm with a constant tangential acceleration. What is the magnitude of this acceleration if the kinetic energy of the particle becomes equal to 8×10-4J by the end of the second revolution after the beginning of the motion           [2016]
 

1 0.18m/s2  
2 0.2m/s2  
3 0.1m/s2  
4 0.15m/s2  

Ans.

(3)

Here, m=10 g=10-2kg, R=6.4cm=6.4×10-2m,

Kf=8×10-4J, Ki=0, at= ?

Using work energy theorem,

Work done by all the forces = Change in KE

Wtangential force+Wcentripetal force=Kf-Ki

at=Kf4πRm=8×10-44×227×6.4×10-2×10-2=0.0990.1ms-2