Question

Two blocks are connected by a lightweight, flexible cord that passes over a frictionless pulley. If m1 is 3.4 kg and m2 is 9.1 kg, and block 2 is initially at rest 130 cm above the floor, how long does it take block 2 to reach the floor?

Answer 1

Note: the two blocks are suspended vertically by the string passing over a pulley.

m1=3.4 kg
m2=9.1 kg
H=1.3 m
Let tension = T
acceleration = a
acceleration due to gravity = g

Consider block 1:
Net upward force, F1 = T-m1.g
F1.a = T-m1.g

Consider block 2:
Net downward force, F2 = m2.g - T
F2.a = m2.g - T

Solve for T and A.
Use kinematics equation to solve for time: H=v0.t + (1/2)at²
where v0 = initial velocity=0 m/s, and
t=time in seconds.