Block A has a mass of 300 kg and rests on a smooth table and

Block A has a mass of 3.00 kg and rests on a smooth table and is connected to block B, which has a mass of 2.00 kg, after passing over an ideal pulley, as shown. Block B is released from rest. How long does it take block B to travel 80.0 cm? 0.404 s 0.494 s 0.639 s 0.785 s 0.935 s

Solution

mass of block A = 3kg

mass of block B = 2kg

let acceleration of block B = \' a \' m/s^2

Distance travelled = 0.8 m

we know that acceleration due to gravity (g) = 9.81 m/s^2

F=ma
2g=(2+3)a

a = (2*9.81)/5

a = 3.924 m/s^2 ------> accleration of block B

from kinematic equaitons

s= ut + (a*t^2)/2

but here intial velocity of block B is zero => u=0

s = (a*t^2)/2

t= sqrt(2s/a)

t = sqrt ((2*0.8)/3.924)

t = 0.6385 sec = 0.639 sec