A horizontal trolley of mass 50kg is pulled by a steady horizontal force of 140N. When an additional load of 30kg is placed on the trolley, the same pulling force produces an acceleration of 1.2ms−2. Assume the frictional force is the same in both cases.
(a) Calculate the magnitude of the frictional force acting on the trolley.
(b) Determine the acceleration of the trolley when it moves without the extra load.