Physics Past Questions and Answers

(a) Explain how a gas can be made to conduct electricity.<br/>(b) Name the electric charge carriers in gases.

The diagram above represents the graph of electron energy against the frequency of the radiation incident on a metal surface. Interpret the: (a) slope of the graph; (b) intercept, OC; (c) intercept, OK.

(a) State two conditions under which photo-electrons can be emitted from the surface of a metal.<br/>(b) List two particle characteristics of electromagnetic waves.

(a) Give two examples each of:<br/>(i) rotational motion;<br/>(ii) linear motion.<br/>(b) Describe a laboratory experiment to determine the density of an irregularly shaped solid.<br/>(c) State Newton's second law of motion<br/>(d) Explain the term inertia.<br/>(e)<br/><br/>The diagram above illustrates a body of mass 5.0 kg being pulled by a horizontal force F. If the body accelerates at 2.0 ms\(^{-2}\) and experiences a frictional force of 5 N, calculate the:<br/>(i) net force on it;<br/>(ii) magnitude of F;<br/>(iii) coefficient of kinetic friction. [ g = 10 ms\(^{-2}\)]<br/> <br/>

a) Define heat capacity and state its unit.<br/>(b) List two effects of heat on a substance.<br/>(c) Explain how a tightly fitted glass stopper could be removed from a reagent bottle.<br/>(d) A quantity of pepper soup of mass 800 g poured into a plastic container with a tight-fitting lid has a temperature of 30°C. The container is then placed in a microwave oven, rated 1200 W and operated for 3 minutes.<br/>(i) Calculate the final temperature attained by the soup. (Assuming no heat losses).<br/>(ii) Explain why containers with tight-fitting lids are not suitable for use in microwave cooking.<br/>(iii) When the soup is brought out and allowed to cool, a dent is observed on the container. Explain. [Take specific heat capacity of the soup = 4000 Jkg\(^{-1}\) K\(^{-1}\)]