Ncert – class 8- science – Chapter 8: Force and Pressure 1 Welcome to your Ncert - class 8- science - Chapter 8: Force and Pressure 1 1. Two forces F1 and F2 are acting on a body. F1 is a contact force. F2 is a non - contact force. Then, the body (if at all moving) always moves in direction of F2 F1 Force whose magnitude is greater None of these None 2. A vehicle sinks into soft ground. The vehicle is changed so that it does not sink as far. Which change is made? Wheels that are further apart A more powerful engine Wider tyres A lower centre of mass None 3. To move at the same speed, a car with a flat face and another with a streamlined body will require a different amount of force from the engine. The engine of the streamline bodied car will: Exert more force Exert zero force Exert less force Exert no force None 4. Consider the following two cases which involve the motion of an objectCase 1: An apple falling from a tree towards the ground.Case 2: To move a loaded cart on the horizontal ground. Case 2: Involves loaded cart to be moved by pulling force only Case 2: Involves loaded cart to be moved by both pulling or pushing force Case 1: Involves pulling of apple by earth magnetic force Case 1: Involves pushing of the apple by earth's gravitational force None 5. A force is needed to : Change the state of motion or state of rest of the body Keep the body in motion Keep the body stationary Keep the velocity of body constant None 6. With the increase in the area of contact of an object the pressure decreases increases none of these is not affected None 7. The force between two charge bodies is called magnetic force muscular force gravitational force electrostatic force None 8. When three forces of 50N, 30N and 15N act on a body, then the body is Moving with an acceleration At rest In equilibrium Moving with a uniform velocity None 9. Which of the following is a contact force: Frictional force Magnetic force Electrostatic force Gravitational force None 10. Consider two shoulder bags, one with a thin strap, and the other with a wide strap. If both the bags are equally heavy, the bag with the wide strap will be more comfortable to carry because the wide strap allows friction to be spread over a bigger area, thus reducing force between shoulder and the strap the thin strap has greater inertia per unit length the wide strap enables the weight of the bag to be spread over a bigger area, thus reducing the pressure on the shoulder. the thin strap causes greater momentum to be exerted None 11. Which of the following is a correct statement regarding the pressure due to fluids? Force acting on the wall due to pressure is always perpendicular to it because of collision between the molecules takes place at any direction to it but its normal reaction on the wall is always perpendicular to it. Force acting on the wall due to pressure is always oblique to it because of collision between the molecules takes place perpendicular to it. Force acting on the wall due to pressure is always perpendicular to it because of collision between the molecules takes place oblique to it. Force acting on the wall due to pressure is always perpendicular to it because of collision between the molecules takes place perpendicular to it. None 12. The non-contact force is : Force of the friction Force of reaction Tension in string Force due to gravity None 13. It is recommended that the air pressure in motor car tyres be reduced for a motion of the motor cars on sand because inflated tyres cause high pressure on the sand deflated tyres cause low pressure on the sand inflated tyres cause low pressure on the sand deflated tyres cause high pressure on the sand None 14. Which of the following statement is incorrect: Air is compressible at constant temperature At high altitude air pressure is relatively low Density of a gas is directly proportional to its pressure at constant temperature. At high altitude density of air is relatively high None 15. Which of the following statements is /are true Metecors that enter earth atmosphere burn up due to non-contact Magnet force is a non contact force Contact forces are always observes than non-contact forcs. The strength of a non contact force is independet of distance between the bodies. None 16. In the superhit film 'Raja Hindustani', Amir Khan greets his beloved by shaking hand. What kind of force do they exert? Weak Electromagnetic Nuclear Gravitational None 17. Change in the state of rest or of uniform motion is brought about by: Force None Acceleration Energy None 18. Which of these is an example of a non-contact force? A toy car slides down the ramp A child lifts a book lying on the table A marble rolling on the carpet slows down A bar magnet moves a paperclip without touching it None 19. Write true or false. Correct the false statements. Wooden sleepers are placed under railway tracks in order to increase pres. pressure is independent of the roughness of the surfaces in correct. The perpendicular distance from the pivot of a rotating body to the line of known as the moment arm. pressure is inversely proportional to the force applied None 20. A tall vertical cylinder filled with water is kept on a horizontal table top. Two small holes A and B are made on the wall of the cylinder, A near the middle and B just below the free surface of water. Water jet through A will have larger range Water jets through A and B will have equal range There will be no water jet through B Water jet through B will have larger range None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
