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)

Development

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)

· Ask that does it return to its original shape when hands are removed. (Response: No.)

· 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

Follow up

· Survey the classroom to find things that need either a push or a pull to make them move in different directions.

· Discuss where pushes and pulls changes the shape of different objects in everyday life and enlist them.

· Find two materials in which objects regain their original shape after the removal of applied force.

· Find two materials in which objects change their shape on applying force but don’t regain their original shape on removal of applied force. Draw their pictures: