Danger can u explain a bit more....
I mean reaction to the action of crankshaft will be in the form of friction on clutch and other parts which engine has to overcome while rotation. So why whole body rolls!!!!!!!
It amazes me!
It was explained, but not clearly pointed out. The rotational motion of the motor and driveshaft is easy enough to understand. Why one side of the car jacks up is because as the tires grip the road under the load, the mass of the car resists the force provided by the motor. Since there is a "resistive force" transmitted back through the axle and differential, the rotational force at the driveshaft will no longer transmit the full force into accelerating the car, but rather starts to twist the entire rear axle around the axis of the driveshaft. To see it more clearly, try imagining such a car with the tires glued to the groud so that the tires cannot rotate. If the tires can't rotate, any torque provided by the motor through the driveshaft will cause the axle to rotate along the axis of the driveshaft in the opposite direction of the driveshaft. As a solid rear axle is suspended from the vehicle, it is allowed to move somewhat independently of the chassis and will jack up the side that is pushing down on the ground. Do keep in mind that the motor is attached to the chassis up at the front of the car, so that is the point where torque force acts opposite to the axle.
Lastly, you won't see this occur in a car with an independent rear suspension as the differential is essentially bolted to the chassis and the axles aren't able to transmit force in the direction of the ground (since they are jointed at each end).