Physics Past Questions and Answers

A machine has a velocity ratio of 5. It requires a 50kg weight to overcome a 200kg weight. The efficiency is

A 4%
B 5%
C 40%
D 50%
E 80%

Question 267:

If the normal atmospheric pressure in a laboratory supports a column of mercury 0.76m high and the relative density of mercury is 13.8, then the height of water column which atmospheric pressure will support in the same laboratory at the same time is

A 0m
B 10m
C 13m
D 14m
E 18m

Question 268:

An electric current of 3Aflowing through an electric heating elements of resistance 20 embedded in 1,000g of an oil raises the temperature of the oil by 10oC in 10 seconds then the specific heat capacity of the oil is

A 1.8Jg-1oC
B 0.6Jg-1oC
C 0.18Jg-1oC
D 18Jg-1oC
E 0.06Jg-1oC

Question 269:

The difference of potential between the terminals of cells is 2.2 volts. When a 4ohm resistor is connected across the terminals of this cells, the potential difference is 2 volts. What is the internal resistance of the cell?

A 0.10 ohms
B 0.25ohms
C 0.40ohms
D 2.50ohms
E 4.00ohms

Question 270:

Which of the following best describes the energy changes which take place when a steam engine drives a generator which lights a lamp?

A Heat \( \to \) light \( \to \) sound \( \to \) kinetic
B Kinetic \( \to \) light \( \to \) heat \( \to \) electricity
C Heat \( \to \) kinetic\( \to \) electricity \( \to \) heat \( \to \) light
D Electricity \( \to \) kinetic \( \to \) heat v light
E Heat \(\ to \) sound \( \to \) kninetic v electricity