A ball is thrown up into the air. At the highest point of its trajectory the ball:

• Is accelerating downwards

• has zero acceleration

• is accelerating upwards

• is still moving upwards

A ball of mass 200 g moving with a velocity of 8 m/s collides and sticks with another ball of mass 300 g moving in the same direction with velocity 4 m/s. What is the common velocity of the balls after the collision?

• 5.6 ms-1

• 2.8 ms-1

• 11.2 ms-1

• 1.4 ms-1

A boy holds the end of a rubber cord from which hangs a solid metal ball, if the boy whirls the ball in a horizontal circle, keeping his hand still. If the rubber cord breaks when the ball is at a point on the circle, in what direction will the ball move?

• towards the hand of the boy

• away from the hand of the boy

• in the direction of the tangent to the circle at the point of break

• None of the above

A force of 20 N applied parallel to the surface of horizontal table is just sufficient to make a block of mass 4 kg set for motion. Find the acceleration when the force is doubled.

• 2 ms-2

• 4 ms-2

• 5 ms-2

• 10 ms-2

A man walks 1 km due east and then 1 km due north. His displacement is

• 1 km N15°E

• 1 km N30°E

• √2 km N45°E

• 2 km N75°E

A motor car moves with a velocity of 20 ms-1 on a rough horizontal road and covers a displacement of 50 m. Find the coefficient of dynamic friction between the type and the ground (g = 10 ms-2)

• 0.3

• 0.6

• 0.5

• 0.4

A physics student standing on the edge of a cliff throws a stone vertically downward with an initial speed of 10.0 m/s. The instant before the stone hits the ground below, it is traveling at a speed of 30.0 m/s. If the physics student were to throw the rock horizontally outward from the cliff instead, with the same initial speed of 10.0 m/s, what is the magnitude of the velocity of the stone just before it hits the ground?

• 10.0 m/s

• 20.0 m/s

• 30.0 m/s

• 40.0 m/s

A quantity is defined as the product of cross-sectional area and change in momentum per unit length. Which of the following is its SI unit?

• Nm

• kgs-1

• kgm2s-1

• Nkgs-1

A rectangular concrete block 40 cm x 30 cm x 60 cm of mass 10 kg rests on a horizontal flat surface. What is the minimum pressure it can possibly exert on the surface?

• 816.6 Nm-2

• 816.6 Nm2

• 408.3 Nm-2

• 608.4 Nm

A simple hydrometer consists of uniform cylinder suitably weighted to float upright in most common liquids. It is graduated to read the relative density of a liquid directly. Which of the following is NOT correct?

• When placed in a liquid, it displaces exactly its own weight of the liquid

• Its graduation increases from top to base

• When placed in a liquid, it displaces exactly its own volume of the liquid

• The product of the volume and density of liquid displaced is equal to its mass