A spring balance,which is suspended from the roof of a lift, carries a mass of 1kg at its free end. If the lift accelerates upwards at 2.5ms-2, determine the reading on the spring balance. [g = 10ms-2]
A
24.0N
B
12.5N
C
7.5N
D
4.0N
Verified Correct Answer: B.
Physical Principles & Numerical Solution
F = ma
= 1 x 2.5 = 2.5N
weight = mg = 1 x 10 = 10N
Reading = F + Wt = 2.5 + 10
= 12.5N
Source: Myschool Past Questions Archive (Record #33864)