The equation of a wave is y = 0.005 sin[x(0.5X - 200t)] where x and y are in meters and t is in seconds. What is the velocity of the wave?

• A. 4000ms^-1
• B. 400ms^-1
• C. 250ms^-1
• D. 40ms^-1

Which of the following is used to measure relative humidity?

• A. hydrometer
• B. barometer
• C. hypsometer
• D. hygrometer

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

Which of the following statements about mass and weight are correct? i. Weight is the force of gravity on a body. ii. The mass of a body is the quantity of matter in the body. iii. The weight of a body is greatest at the equator. iv. The mass of a body is greatest at the poles

• A. i and ii only
• B. i and iii only
• C. ii and iv only
• D. iii and iv only

According to kinetic molecular model in gases,

• A. the particles are closely packed together; they occupy minimum space are usually arranged in a regular pattern
• B. the particles vibrate about fixed positions and are held together by the strong intermolecular bonds between them
• C. the molecules are very far apart and occupy all the spaces made available to them
• D. the particles occur in clusters with molecules slightly further apart

(a) Explain what is meant by photoelectric emission

(b) Draw a labelled diagram showing the structure of a simple type of a photocell and explain its mode of operation.

(c) State four applications of photoelectric emission.

(d) In a photocell, no electrons are emitted until the threshold frequency of light is reached. Explain what happens to the energy of the light before emission of electrons begins. State one factor that may affect the number of emitted electrons.

An empty density bottle weighs 2 N. if its weighs 5 N when filled with water and 4 N when filled with olive oil, the relative density of olive oil is

• A) 1/3
• B) 2/3
• C) 1/5
• D) 2/5

Lodestone is a natural magnet, it points at

• A. N – W when suspended freely
• B. N–S when suspended freely
• C. S – E when suspended freely
• D. S–W when suspended freely

Which of the following machines does not apply the lever principle?

• A. Claw hammer
• B. Wheelbarrow
• C. Single pulley
• D. sugar tong

Calculate the amount of heat generated in an external load of resistance 8Ω if an alternating current of peak value 5A is passed through for 100s.

• A. 20,000J
• B. 10,000J
• C. 5,000J
• D. 4,000J