Friction Worksheet-4

Friction Worksheet-4

1. Which one of the following statements is not true?

(a) Friction helps us to twist an object

(b) Friction is a force that opposes motion

(c) Objects have weight because of the frictional force between them and the Earth

(d) More friction is produced between rough surfaces than between smooth surfaces.

2. A box is given a push across the floor. It comes to a stop shortly after. Which one of the following reasons explains why this happens?

(a) Gravity is acting on the box in the direction opposite to the box's movement

(b) Friction is acting on the box in the same direction of the box's movement

(c) Friction is acting on the box in the direction opposite to the box's movement

(d) The heat produced by the box's movements slows down the box.

3. Which one of the following does not help to reduce friction?

(a) Grease                                      (b) Soapy water

(c) Oil                                             (d) Sand

4. Ram pushes the box by applying a force of 500 N in horizontal direction so that the box slides along the floor as shown in fig. Find the point where the frictional force acting on the box is maximum

(a) P                    (b) Q                   (c) R                    (d) P, Q & R

5. The force of friction between two bodies is

(a) Parallel to the contact surfaces

(b) Perpendicular to the contact surfaces

(c) Inclined at 30° to the contact surfaces

(d) Inclined at 60° to the contact surfaces

6. The deep grooves in the tyres of the tractor

(a) Decrease friction                    (b) Increase friction

(c) Make it stable                          (d) Make type more attractive

7. Why do we move faster on roller-skates than on shoes?

(a) The roller-skates have rollers to reduce friction

(b) The roller-skates have more surface in contact with the ground

(c) The roller-skates have no gravitational force

(d) The roller-skates absorb heat from the ground

8. We need energy to overcome friction. During friction, unwanted heat energy is produced. Frictions can be reduced by the use of ______.

(I) Rollers, (II) Gears, (III) Lubricants, (IV)  Ball bearing

(a) (I), (II) & (III)                         (b) (I), (III) & (IV)

(c) (II), (III) & (IV)                      (d) (I), (II) & (IV)

9. Which of the following are advantages of friction?

(I)     Soles of shoes become worn out

(II)   An old man walking on a foot path

(III)  A car slows down when brakes are applied

(a) (I) & (II)                                   (b) (I) & (III)

(c) (II) & (III)                                (d) None of these

10. A man sharpens his knife as shown in figure. Which of these properties of friction are in use?

(I)     Friction helps us to hold objects

(II)   Friction acts in the opposite direction of motion

(III)  Friction causes the surfaces in contact to wear away

(IV)  Friction produces heat energy

(a) (I) & (II)                                   (b) (I), (III) & (IV)

(c) (III) & (IV)                               (d) All of these

Answer Key:

(1)-(a); (2)-(c); (3)-(d); (4)-(a); (5)-(a); (6)-(a); (7)-(a); (8)-(b); (9)-(c); (10)-(d)