Force and pressure Worksheet-13

Force and pressure Worksheet-13

56. In the following situations identify the agent exerting the force and the object on which it acts. State the effect of the force in each case.

(a) Squeezing a piece of lemon between the fingers to extract its juice.

(b) Taking out paste from a toothpaste tube.

(c) A load suspended from a spring while its other end is on a hook fixed to a wall.

(d) An athlete making a high jump to clear the bar at a certain height.

57. (a) While constructing dams, the base is made more wide. Why?

(b) Why does blood ooze out when there is a slight cut on your body?

58. What do you do to get maximum pressure with a minimum force? Name at least one appliance based on this principle.

59. (a) Define atmospheric pressure.

(b) What happens to the atmospheric pressure on mountains?

(c) What makes a balloon stretch if it is filled with air?

60. (a) Define one atmosphere.

(b) Where is the pressure greater, 10 m below the surface of sea or 20 m below?

(c) Where is pressure greatest and the least inside a bottle filled with water.

61. (a) What is weight?

(b) What is the unit of weight?

(c) Name the device used for measuring the weight of an object.

(d) Can weight be taken as a measure of force?

62. Name the type of force in the following cases.

(a) Raindrops falling on the earth.

(b) Holding a book on your hand.

(c) Running a comb through your dry hair.

(d) A bar magnet suspended freely.

(e) Bullocks ploughing the field.

63. What happens to the atmospheric pressure if.

(a) The temperature is high.

(b) The humidity in air increases.

(c) Metrological office predicts fair weather.

(d) There is a storm.

(e) The weather is dry.

64. Define friction.

Why do we rub our hands in winter?

Answer:

56. Agent exerting the force Object Form in which affect of force is observed

(a) Fingers Lemon Lemon juice comes out.

(b) Fingers Toothpaste tube Toothpaste comes out.

(c) Spring Load Load is suspended.

(d) Athlete Bar Jumping.

57. (a) The pressure of liquids increases as the depth increases. Therefore, the base is made wider to    withstand the high pressure of water. Since pressure is inversely proportional to area.

(b) Blood pressure is little greater than atmospheric pressure. Due to this, the blood oozes out when we have a slight cut on our body.

58. As pressure is inversely proportional to area and directly proportional to force, so to get maximum pressure with a minimum force we can decrease the area.

Sharp knife, pointed nails are based on this principle.

59. (a) Atmospheric pressure is the pressure exerted by air.

(b) As we go on the mountains, the atmospheric pressure decreases.

(c) The air exerts pressure on the balloon and therefore, it stretches.

60. (a) The pressure which can support 76 cm of mercury in a mercury barometer is called one atmosphere.

(b) 20 m below the surface of sea the pressure is greater.

(c) The pressure is greatest at the bottom and least on the surface of water filled in a bottle.

61. (a) Weight of an object is the force of gravity acting on the object.

(b) Unit of weight is Newton or kilogram weight.

(c) Spring balance is used for measuring the weight of an object.

(d) Yes, the weight can be taken as a measure of force.

62. (a) Force of gravity.

(b) Force of gravitation (weight).

(c) Electrostatic force.

(d) Magnetic force.

(e) Muscular force.

63. (a) Atmospheric pressure decreases.

(b) Atmospheric pressure decreases.

(c) Atmospheric pressure increases.

(d) Atmospheric pressure decreases.

(e) Atmospheric pressure increases.

64. Friction is the force which comes into play when one object moves on the surface of another. When we rub our hands in winter, due to the force of friction, heat is generated. Therefore, we feel warm.