Physics20 ss1

The depolarising agent in a Leclanche cell is?

• carbon rod

• ammonium chloride

• manganese (IV) oxide

• zinc plate

Which of the following statements explain why hot soapy water is more effective in cleaning oil-stained dishes?

• The oil on the dishes repels the soap

• soap and heat decrease the surface tension of oil

• soap increases the surface tension of oil and water

• Hot water increases the surface tension of oil

The earpiece of a telephone handset converts energy from

• electrical to sound

• sound to electrical

• sound to electrical

• sound to radio wave

Two identical cups containing the same volume of water at 45°C and 5°C, are left in a room at 25°C. Which of the following graphs correctly illustrates the variation of temperature with time?

• A

• B

• C

• D

The length of an iron bar is 100cm at 20°C. At what temperature will its length increase by 0.01%? [Linear expansivity of iron = 1.2 x 10⁻⁵ °C⁻¹]

• 48.0°C

• 38.0°C

• 28.3°C

• 23.0°C

A 500 N box rests on a horizontal floor. A constant horizontal force is exerted on the box so that it moves through 8 m. If the coefficient of kinetic friction between the floor and the box is 0.22, calculate the work done on the box.

• 880J

• 440J

• 400J

• 110J

Which of the current-voltage characteristics shown below is that exhibited by an ohmic conductor?

• 
• 
• 
• 

A motorcycle starting from rest is uniformly accelerated such that its velocity in 10 s is 72 kmhr⁻¹. What is its acceleration?

• 108ms⁻²

• 86ms⁻²

• 4ms⁻²

• 2ms⁻²

The temperature of an object is raised by 120 °C. The resulting increase in its absolute temperature is

• 50 K

• 120 K

• 200 K

• 393 K

A diver steps off a diving platform that is 10m above the water. If there is no air resistance during the fall, there will be a decrease in the diver's

• gravitational potential energy

• total mechanical energy

• kinetic energy

• momentum