Simple Machines - Jamb Physics Past Questions and Answers

Question 16:

• JAMB 1994

Calculate the velocity ratio of a screw jack of pitch 0.3cm if the length of the tommy bar is 21cm

A. \(\frac{1}{140}\)\(\pi\)
B. 14\(\pi\)
C. 70\(\pi\)
D. 140\(\pi\)

Question 17:

• JAMB 1997

An electric water pump rate 1.5 kW, lifts 200kg of water through a vertical height of 6 meters in 10 seconds. What is the efficiency of the pump? [g = 10ms-2, neglecting air resistance]

A. 90.0%
B. 85.0%
C. 80.0%
D. 65.0%

Question 18:

• JAMB 1998

In a wheel and axle mechanism the diameters of the wheel and axle are 40cm and 8cm respectively. Given that the machine is 80% efficient, what effort is required to lift a load of 100N?

A. 20N
B. 25N
C. 50N
D. 80N

Question 19:

• JAMB 2000

The velocity ratio of a machine is 5 and its efficiency is 75%. What effort would be needed to lift a load of 150N with the machine?

A. 20N
B. 30N
C. 40N
D. 50N

Question 20:

• JAMB 2001

The efficiency of a machine is always less than 100% because the

A. Work output is always greater than the work input
B. Load lifted is always greater than the effort applied
C. Effort applied is always greater than the load lifted
D. Velocity ratio is always greater than the mechanical advantage