force and pressure class viii all questions answer requred
Answers
1. Give two examples each of situations in which you push or pull to change the state of motion of objects
Soln:
Examples of situations in which you push or pull to change the state of motion of objects.
1. Pull situations
a) In order to open a drawer, we have to pull it. This action changes the state of motion of the drawer.
b) To draw water from the well, the rope is pulled. This action changes the state of motion of the bucket.
2. Push Situations
a) A football is pushed by the foot of a player. This action changes the state of motion of the ball.
b) In order to change the place of the heavy box from one room to another, we have to push it. This action changes the motion of the box.
2. Give two examples of situations in which applied force causes a change in the shape of an object.
Soln:
The forces which change the shape of an object are as follows:
i) By pressing the clay between the hands, it deforms.
ii) The shape of the plastic bottle changes by squeezing it.
3. Fill in the blanks in the following statements.
(a) To draw water from a well we have to __________ at the rope.
(b) A charged body __________ an uncharged body towards it.
(c) To move a loaded trolley we have to __________ it.
(d) The north pole of a magnet __________the north pole of another magnet.
Soln:
To draw water from a well we have to pull at the rope.
A charged body attracts an uncharged body towards it.
To move a loaded trolley we have to pull or push it.
The north pole of a magnet repels the north pole of another magnet.
4. An archer stretches her bow while taking aim at the target. She then releases the arrow, which begins to move towards the target. Based on this information fill up the gaps in the following statements using the following terms.
muscular, contact, non-contact, gravity, friction, shape, attraction
(a) To stretch the bow, the archer applies a force that causes a change in its __________.
(b) The force applied by the archer to stretch the bow is an example of __________ force.
(c) The type of force responsible for a change in the state of motion of the arrow is an example of a __________ force.
(d) While the arrow moves towards its target, the forces acting on it are due to __________ and that due to __________ of air
Soln:
(a) To stretch the bow, the archer applies a force that causes a change in its shape.
(b) The force applied by the archer to stretch the bow is an example of muscular force.
(c) The type of force responsible for a change in the state of motion of the arrow is an example of a contact force.
(d) While the arrow moves towards its target, the forces acting on it are due to gravity and that due to friction of air.
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