25 A plank AB 3.0 m long weighing 20 kg and with its centre of gravity 2.0 m from the end A
carries a load of mass 10 kg at the end A. It
tests on two supports at C and D as shown in
RIA
R2
2.0 m
A
D
B
50 cm
28
50 cm
10 kg
Fig. 4.49
Ti) Compute the values of the reaction
forces R, and R2 at C and D.
2​

Agghh a

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.