Forces, motion and energy activities

Push, pull and move

Compare forces, mass, inertia and the paired pushes between objects.

1. 1

   Can balanced forces act on a moving object?

   Pull one trolley with two helpers against one, then with equal teams. Does balancing the pulls stop a rolling trolley?

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2. 2

   How do force and mass change acceleration?

   Can the same push move a heavier cart as easily? Keep the push the same and compare a light cart with a heavy one. Watch the speed gained in the same four seconds.

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3. 3

   Why does a moving object not always need another push?

   What makes a rolling cart slow down? Compare the same starting speed with and without a resisting force. Inertia is not another forward push.

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4. 4

   What sets the stopping distance of a sliding object?

   Which change makes the block stop sooner? Keep the starting speed the same and compare weaker and stronger friction. Then try a faster start.

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5. 5

   Why can equal pushes produce different motions?

   Why do two carts move apart at different speeds? A brief push gives both carts equal and opposite impulses. After the push, watch them coast.

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Energy in motion

Explore collisions, stored energy, springs, magnets and pendulums.

1. 1

   What stays the same when two carts collide?

   Do the carts bounce apart or move together? Compare one moving cart hitting a still cart. Keep their masses and starting speed the same when changing the collision.

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2. 2

   Where does stored height energy go?

   Where does the cart’s height energy go? Watch the three energy bars while the cart descends. Compare a smooth descent with a model that transfers some energy to heating.

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3. 3

   Why does a stretched spring pull back?

   Which way does a spring pull? Watch the force arrow on either side of the dashed middle line. At the middle, zero spring force does not mean zero speed.

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4. 4

   When do two magnets push apart?

   Which facing poles make magnets move apart? Read the N and S letters at the two facing ends before pressing Play. The force arrows point in the directions each magnet is pushed.

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5. 5

   What changes a pendulum’s swing time?

   Does a heavier pendulum swing more slowly? Compare complete swings: back to the same side moving in the same direction. Change mass first, then length.

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Keep exploring

Read more in Physical Science encyclopedia articles, with reading controls on each article. For printable practice, explore Maths worksheets and answer guides.