Force and pressure Worksheet-6

Force and pressure Worksheet-6

1. Give two examples of each of situation in which you push or pull to change the state of motion of objects.

2. Give two examples of situations in which applied force causes a change the shape of an object.

3. In the following situations identify the agent exerting a force and the object on which it acts.

State the acts 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.

4. A blacksmith hammers a hot piece of iron while making a tool. How does the force due to hammering affect the piece of iron?

5. An inflated balloon was pressed against a wall after it has been rubbed with a piece of synthetic cloth. It was found that the balloon sticks to the wall. What force might be responsible for the attraction between the balloon and the wall?

6. Name the forces acting on a plastic bucket containing water held above ground level in your hand. Discuss why the forces acting on the bucket do not bring a change in its state of motion.

7. A rocket has been fired upward to launch a satellite in its orbit. Name the two forces acting on the rocket immediately after leaving the launching pad.

8. How can we decide whether an object is moving faster than the other?

9. What is the distance moved by an object in unit time called?

10. How can we change the speed and the direction of a moving body?

Answer:

1. (i) We push a trolly to move it.

(ii) We pull a chair or a table or basket to change their positions.

2. (i) When we press the foam or soft rubber ball or dough their shapes are changed.

(ii) When we stretch the rubber band, then its shape is changed.

(iii) Squeezing a piece of lemon between the fingers

(iv)Taking out paste from a toothpaste tube

3. (a) The fingers are the agents, lemon is the object. The effect of force is the lemon juice being expelled by squeezing.

(b) The hand is the agent, toothpaste tube is object and the coming out of paste from toothpaste tube is the effect of force.

(c) Suspended load is agent, spring is the object, the effect of force can be seen in the form of alongation of spring on suspension of load.

(d) Athlete is the agent, bar is the object. The force can be seen in the form of jump.

4. The force due to hammering causes the change in shape of iron and iron can be molded in the desired shape.

5. Electrostatic force.

6. Muscular and gravitational forces act on plastic bucket. The force acting on the bucket do not bring a change in state of motion because they are acting in opposite direction with equal magnitudes. Therefore the net force on bucket remains zero.

7. (i) Gravitational force, (ii) Force of friction.

8. By their speed.

9. Speed.

10. By applying force.