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

Correct Answer: Option B

B. 12.5N

Explanation

F = ma

= 1 x 2.5 = 2.5N

weight = mg = 1 x 10 = 10N

Reading = F + Wt = 2.5 + 10

= 12.5N