Physics Past Questions and Answers

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 12:

A load of 20N on a wire of cross-sectional area 8 x 10^-7m², produces an extension of 10m². calculate Young's modulus for the material of the wire if its length is 3m

A 7.0 x 10¹¹Nm^-2
B 7.5 x 10¹¹Nm^-2
C 8.5 x 10¹¹Nm^-2
D 9.0 x 10¹¹Nm^-2

Question 13:

A cube of sides 0.1m hangs freely from a string. What is the upthrust on the cube when totally immersed in water? [density of water is 1000kgm^-2, g = 10ms^-2]

A 1000 N
B 700 N
C 110 N
D 10 N

Question 14:

A piece of wire gauze can be made to lie on water because

A The wire guaze is less dense than water
B The water molecules repels the wire guaze upwards
C The water surface has the effect of an elastic thin skin
D Of the cohensive forces between the water and the wire guaze molecules

Question 15:

A liquid of mass 1.0 x 10³kg fills a rectangular tank of length 2.5m and width 2.0m. If the tank is 4m high, what is the pressure at the middle of the tank?[g = 10ms^-2]

A 1.0 x 10⁴Nm^-2
B 2.0 x 10³Nm^-2
C 1.5 x 10³Nm^-2
D 1.0 x 10³Nm^-2