CBSE Class 8 Science Force And Pressure Worksheet

Question. If Samira is driving at a speed of 70 kilometres per hour, approximately how much distance should she keep from the car in front?
(a) It depends on the speed of the car in front
(b) About 15 metres
(c) About 12 metres
(d) About 45 metres

Answer : D

Question. What probably happens to the thinking TIME as the car's speed increases?
(a) The thinking time reduces because the driver can think faster at faster speeds.
(b) The thinking time increases because of the driver's increased concentration.
(c) The thinking time increases because of the driver's reduced concentration.
(d) The thinking time does not change with a change in the car's speed.

Answer : D

Question. There are 8 balls M, N, O, P, Q, R, S and T. 7 of them are identical, the 8th is either heavier or lighter. Only an accurate beam balance with 2 pans is available.
The result of 3 weighings is as shown: 
Which is the odd ball, and is it heavier or lighter?

(a) Q, heavier
(b) M, lighter
(c) O, lighter
(d) It is not possible to tell for sure

Answer : C

Question. Figure 1 shows an arrangement with a single pulley lifting a load.  Figure 2, shows one more pulley attached to the same weight. If the weight pulled in figure 1 is 60 N, what would be the weight that string Q would need to support?

(a) 15 N
(b) 20 N
(c) 30 N
(d) 60 N

Answer : C

Question. Shown below is a diagram of a weightless piston, which can slide in and out of a cylinder. (Assume that the arrangement is air tight) 
The gas inside the cylinder is heated (The dots inside the cylinder represent individual gas molecules).
Which of the following will happen after a few minutes?

Answer : B

Question. Three identical magnets are held as shown and then released together.
What arrangement will they form when they are released?

Answer : B

Question. The table below gives the mass and volume of three objects (P, Q and R). Answer the question based on it.Which statement about the densities of these three objects is correct?

(a) Q is more dense than P
(b) P is more dense than R
(c) P and R have equal densities
(d) Q and R have equal densities

Answer : B

Question. A spring balance was used to measure the force needed to pull a wooden block across different surfaces. The table below shows the results. The force is expressed in Newton. The question is based on this. The force that opposes motion - due to the roughness of the surface - is called & lsquo; Friction'. On which of the above surfaces is the 'friction' greatest?

(a) Carpet
(b) Glazed tiles
(c) Door mat
(d) Door mat

Answer : D

Question. A spring balance was used to measure the force needed to pull a wooden block across different surfaces. The table below shows the results. The force is expressed in Newton. The question is based on thisIf the block is pulled on the wooden surface with a force of 4.1 N, ____________

(a) the block just starts to move.
(b) the block does not move.
(c) the block moves a bit and stops.
(d) the block moves a larger distance and stops.

Answer : C

Question. About how much would a jerry-can (a type of container) having 10 litres of water weigh?
(a) 100 grams
(b) 1 kilogram
(c) 10 kilograms
(d) 20 kilograms

Answer : C

Question. Lata investigated some rocks and recorded her results in a table. Study it and answer the question A harder material can scratch another material which is not so hard. Most hard rocks cannot be split into thin layers. An exception, going by the data above, seems to be:

(a) Shale
(b) Granite
(c) Basalt
(d) Slate

Answer : D

Question. An apartment with ten floors has a water supply design as shown in the figure. If three people on the 1st, 5th and 10th floors open their taps at the same time, where will the pressure be the maximum?

(a) the tenth floor
(b) the first floor
(c) the fifth floor
(d) all the floors will have the same water pressure.

Answer : C

Question. Which of these screws would the easiest to drive into a piece of wood?

Answer : C

Question. Four school bags of the same size and dimensions but with different strap sizes are available. Among these, the strap offering the most comfort while carrying the bag would be ___________.
(a) a 2 cm wide strap
(b) a 3 cm wide strap
(c) a 4 cm wide strap
(d) a 5 cm wide strap

Answer : D

Question. The level of tea in a kettle is shown here. Which of these correctly shows the level of the tea in the kettle later (after some tea has already been poured) while it is being poured into another cup?

Answer : B
 

1) Write one word for the following sentences.

a) A pull or a push on an object is called ______________.

b) A force exerted by a magnet ______________________.

c) A force acting on a unit area of a surface ______________.

d) A pressure exerted by air ___________________.

2) Suppose a man is standing behind a car. Does the man exert the force on the car?

3) If the members of two teams, in a game of tug-of-war, are trying to pull the rope in their respective directions and the rope does not move. Which team pulls with more force.

4) In the figures shown below, what conclusion can you draw about the pressure exerted by liquids.

5. A forced exerted by a magnet on another magnet is
a) contact force
b) Frictional force
c) Non contact force
d) Muscular force

6) The weight of air in a column of the height of the atmosphere and area 10cm x 10cm is as large as
a) 1 Kg.
b) 10 kg.
c) 100 kg.
d) 1000 kg.

7) When air is filled in a container, air
a) Exert pressure at the bottom
B) Exert pressure on upper side.
c) Exert pressure on the walls
d) Non of these

8) The shoulder bags are provided with broad straps.
a) To decrease the pressure
b) To exert more force
c) To increase the pressure
d) None of these.

1. S.I unit of pressure is ____________.

2. The amount or the strength of force is called its_______________.

3. Pressure in solid depends upon ________________ and ____________.

4. Pressure in liquids depends upon _____________ and ______________.

5. Force generated by moving of non living materials is called ______________.

6. Give 2 examples of contact forces.

7. Name the scientist who invented a pump to extract air from a vessel.

8. Name the force which acts upon another body without any connector.

9. Name the type of force involved in the following.
a) To pick your school bag.
b) To collect scrap iron from garbage.
c) To push or pull a loaded trolley ay supermarket.
d) Flying of seeds away from each other in plastic bag when gently rubbed.

10. Name the device used to measure pressure in fluids.

11. How much force is required to lift a mass of 1Kg (10N/1N).

12. A rolling ball stops after sometime due to (gravitational force/ Frictional force).

13. When 2 forces are applied at the same point but in opposite directions the net force is equalto the (sum/ difference) of forces acting separately.

14. Force used to stretch the spring is (muscular force/ magnetic force)

15. Application of force brings the change in
a) shape and size of object
(b) speed and direction of object
(c) position of object
(d) all the above

Q1) Fill in the blanks

a. A force arises due to __________ between two objects.

b. An example of a non-contact force is __________.

c. The pressure exerted by air around us is known as __________.

d. Strength of the force is expressed by its __________.

e. Application of force can change the __________, __________ and __________ of an object.

f. Force exerted by our muscles is called __________ force.

g. Direction of force of friction is always __________ to the direction of motion.

h. Force per unit area is called ___________.

Q2) Complete the following sentences:
a. If two equal forces act in the opposite directions on an object, the net force acting on it is __________.
b. It is easier to cut with a sharp knife than with a blunt one because _________ ____________.
c. Porters place a round piece of cloth on their heads, when they have to carry heavy loads because ____________ _____________

Q3) Give four effects of force. Write one example of each.

Q4) Name
a) the force exerted by all matter on all other matter
b) the force which tends to slow down objects or keep them from moving
c) the force with which a charged body attracts an uncharged body.

Q5) An example of a contact force is
1) Magnetic force
2) Frictional force
3) Gravitational force
4) All of these

Q6) A Force cannot change the
1) Speed of an object
2) Mass of an object
3) Shape of an object
4) The direction of a moving object

Q7) The pull of the earth is a force called
a) Gravitational force
b) Frictional force
c) Electrostatic forces
d) None of these

Q8) If a force is applied on a smaller area of contact, the pressure exerted by it is
1) Greater
2) Lesser
3) The same
4) None of these

Q9) Why do the pillars holding the track of Metro trains have a broader base?

Q10) Define Pressure. Explain why shoulder bags are provided with broad straps and not thin strap.

Q11) Describe an activity to show that
(i) the pressure exerted by a liquid at the bottom of the container, depends on the height of its column.
(ii) liquids exert pressure on the walls of the container.
(iii) liquids exert equal pressure at the same depth.

Q12) Explain why we do not feel the atmospheric pressure.

Q 13) A ball rolling on the ground comes to rest after some time. Name the force involved.

Q 14) Explain the following types of forces. Give one example where each of these could be found operating:
a. Magnetic force c) Electrostatic force
b. Gravitational force d) Frictional force

Q15) Bhola was impressed by the miracle performed by baba Shyamdev, when Baba lied down on a bed of nails. The nails did not hurt him. Bhola narrated this miracle to his friend Rahul. Rahul explained to Bhola that, there is no magic or miracle here. Even he can do the same trick.
(a) Why did Rahul say that , there is no miracle in this trick? Why did Baba Shaymdev not hurt himself?
(b) Which quality is shown by Rahul here?