Deck 11: Pressure in Fluids

Question 1

Determine the force applied tangentially to a bar of a screw-jack at a radius of 60 cm, if the torque required is 750 N m.

Answer 1

Question 2

Calculate the torque developed by a motor whose spindle is rotating at 900 rev/min and developing a power of 4.20 kW.

Answer 2

Question 3

A motor connected to a shaft develops a torque of 8 kN m. Determine the number of revolutions made by the shaft if the work done is 7.2 MJ

Answer 3

Question 4

Question 5

An electric motor has an efficiency of 72% when running at 1400 rev/min. Determine the output torque when the power input is 2.50 kW

Question 6

A circular piston exerts a pressure of 150 kPa on a fluid when the force applied to the piston is 0.5 kN. Calculate the diameter of the piston, correct to the nearest millimetre.

Question 7

Question 8

Question 9

Question 10

Question 11

A block of aluminium having a mass of 20 kg cools from a temperature of 250C to 80C. How much energy is lost by the aluminium? Assume the specific heat capacity of aluminium is 950 J/(kg C).

Question 12

Calculate the heat energy required to convert completely 12 kg of water at 30C to superheated steam at 100C. Assume that the specific heat capacity of water is 4200 J/(kg C) and the specific latent heat of vaporisation of water is 2260 kJ/(kg C).

Question 13

An electric furnace has an efficiency of 62% and is rated at 7.5 kW. 20 kg of copper at 23°C is placed in the furnace until it melts at 1079°C. If the specific heat capacity of copper is assumed to be 0.39 kJ/(kg°C) and the latent heat of fusion is 180 kJ/(kg°C), calculate the time taken for the furnace to melt the copper.