Physics Past Questions and Answers

a load of mass120kg is raised vertically through a height of 2m in 30s by a machine whose efficiency is 100%. Calculate the power generated by the machine. [g = 10ms^-2]

A 60W
B 80W
C 100W
D 120W

Question 857:

A block and tackle system has 6 pulleys. If the efficiency of the machine is 60%, determine its mechanical advantages

A 12.0
B 10.0
C 3.6
D 1.8

Question 858:

Which of the following actions will improve the efficiency of the pulley system?

A Reducing the mass of the pulley
B Increasing the friction force between the string and the pulley
C Increasing the mass per unit length of the string of the pulley
D Increasing the mass of the pulley

Question 859:

The ice and steam points of a certain thermometer are -20^o and 100^o respectively. Calculate the Celsius temperature temperature corresponding to 70^o on the thermometer

A 84.0^o
B 75.0^o
C 64.0^o
D 58.0^o

Question 860:

The silver coating on the inside of a vacuum flask reduces heat loss by

A Conduction
B Radiation
C Condensation
D Convention