PHY F4 FORCES & MOTION (II)

Diagram 8 shows two identical plasticine balls, P and Q, dropped from the same height onto two different objects. Which of the following is the same for both P and Q?

• Impulsive force

• Impulse

• Time of impact

• Deceleration

Diagram 9 shows the variation of force with time of Impact when a tennis ball hits a wall. What is the total impulse experienced by the tennis ball due to this impact?

• 2 Ns

• 4 Ns

• 20 Ns

• 100 Ns

Which feature can improve the safety of passengers in a car?

• Power steering

• Sport rims

• Metallic paint

• Air bag

Braking gradually is safer than braking suddenly because

• the passengers are likely to be thrown forward

• there will be less wear and tear to the tyres when braking gradually

• the impulsive force on the passengers will be lesser when braking gradually.

• the car will stop in a shorter distance when braking gradually.

Gravitational acceleration on the Moon's surface is less than on the Earth's surface. As a result,

• objects fall with greater speed on the Moon's surface.

• objects have smaller mass on the Moon's surface.

• objects have smaller weight on the Moon's surface.

• objects have smaller density on the Moon's surface.

The mass of an object is 200 g. If it falls freely to the ground with an acceleration of 10 ms^-2, what is its weight?

• 2000 N

• 200N

• 20N

• 2N

Diagram 10 shows an aeroplane flying with a constant velocity at a constant height. Which pair of forces must have the same magnitude?

• F₁ and F₃

• F₃ and F₂

• F₄ and F₃

• F₁ and F₄

Diagram 11 shows a man pulling a trolley with a rope. What is the magnitude of the horizontal force when the trolley is pulled?

• 16.7 N

• 150 N

• 250 N

• 433 N

A trolley is pushed with a force along a horizontal path through a distance. The variation of force with distance moved is shown in Diagram 12. The total work done by the force in moving the trolley by 14 m is

• 112 J

• 96 J

• 80 J

• 64 J

A stone is thrown vertically upwards from the ground. It reaches a maximum height of h and returns to the ground. Diagram 13 shows the motion of the stone. At which position, Q, R, S or T, the kinetic energy is the same with the potential energy?

• Q

• R

• S

• T