# Effects of Forces

#### Students’ Learning Outcomes

·         Demonstrate how force can change the position and the shape of an object.
·         Explore that greater the force, greater the change in the distance covered by the object.
·         Design experiments to demonstrate that some objects can return to their original shape after the release of force. Information for Teachers
·         When a push or pull is applied to an object, it changes its position or it changes its shape.
·         The greater the force, greater the change in the distance covered by the object.
·         Some objects return to their original shape after the release of force and some don’t.

#### Material / Resources

Ball, coins, rubber bands, kitchen sponge, balloon, clay, textbook

#### Worm up activity

·         Place a ball on the floor.
·         Ask the students how can they move this ball?
·         Ask a student to move the ball.
·         Then ask another student to push it harder.
·         What happens when you apply more force on the ball?
(Conclude that greater the force, greater the distance covered by the object)
·         Give a rubber band to a student ask him/her to stretch it softly. Then ask: Does the shape of rubber band change when stretched?
(Students’ response: force changes its shape)

#### Activity

·         Place a coin on the table.
·         Ask students to observe the position of the coin.
·         Ask one student to push the coin gently. Note the new position as well as the distance covered by the coin.
·         Ask the same student to push the coin with more force.
·         What difference do you observe in the two cases?
(Students’ response: Greater the force, greater the change in the distance covered by the object)
·         Have other two students try the same activity with a sharpener and eraser and observe the difference in distance covered.

#### Activity 2

·         Give a kitchen sponge to a student and ask him/her to squeeze it.
·         Ask the students: What happens when you squeeze it? (It changes its shape by applying force)
·         What happens when you release it? ( It regains its original shape)
·         What does it show?
(After students response tell them that some objects regain their shapes on removal of force)
·         Ask different students to repeat the experiment with a spring.

#### Activity 3

·         Take an inflated balloon.
·         Ask a student to press the balloon gently by hands.
·         Ask students: What happens when he/she presses the balloon? (It changes its shape)
·         Ask what happens when he/she releases it? (It regain its shape after the removal of force)
·         Repeat the activity with different students.

#### Activity 4

·         Ask a student to a ball of clay and press it with hands inside a mold.
·         Ask the students what happens when you press the clay ball with their hands. (Response: its shape changes)
·         Tell students that some object do not regain their original shape after the removal of the applied       force.

#### Sum up /Conclusion

·         Ask the students: What effects of force did you observe today? Write the correct response on the board:
v  Force can change the position of an object.
v  The greater the force, the greater the distance covered by an object.
v  Force can change the shape of an object.
v  Some object return to their original shape after the release of force and some not.

#### Assessment

·         Ask the following questions from different students and write the correct answers on the board:
v  Which of the things could you change the shape of by applying force.
a)       A plastic ball
b)      A metal toy
c)       A glass cup
v  What happens when you stretch the plastic bottle by your hand and release
a)      It changes shape
b)      It breaks
c)       It regain its shape
v  When you apply greater force on the bicycle pedals
a)      It covers greater distance
b)      It slow down
c)       It stops
v  How could you stop a toy car moving down a slope?
a)      Give it a push
b)      Put hands in its path
c)       It is impossible to stop
v  When a force is applied on a rubber band
a)      Its shape changes
b)      It stays the same
c)       It breaks