En anglais

Touch it or not: contact and non-contact forces

Sciences · Forces et mouvement · de 7 à 8 ans

Nom ______________________ Date ____________

A magnet pulls a paperclip without touching it. What kind of force is this?
- Contact force
- Non-contact force
- It is not a force at all
Kicking a ball is a non-contact force.
En entourer un : Vrai Faux
A magnet is held above a metal button on the floor. The button jumps up to the magnet before they touch. What kind of force pulled the button?
- A non-contact force, because the pull happened before they touched
- A contact force, because the button is made of metal
- A contact force, because the button moved up
Which type of force needs two objects to touch each other before it can happen?
- Contact force
- Non-contact force
- Neither, forces never need touching
Sofia sorts 6 forces: pushing a door, pulling a wagon, kicking a ball, rubbing hands together, a magnet pulling a pin, and a magnet lifting a clip. How many of the 6 forces are non-contact forces?
Réponse : ______________
Which of these must be true about every non-contact force?
- It needs no touching
- It is always a magnet
- It only pulls on metal
Which of these is a contact force?
- A magnet pulling a fridge magnet
- Pushing a swing
- A magnet pulling a nail from far away
You must touch a magnet directly to feel it pull on metal.
En entourer un : Vrai Faux
Eli pushes a box across the floor. His hands push the box, and the box rubs on the floor as it slides. How many contact forces are at work here?
- One, only the push
- None, the box slides by itself
- Two, the push and the rubbing
Ava says, "If a magnet is close to a paperclip but not touching it, no force can happen between them." Is she right?
- Yes, forces can only happen when things touch
- Yes, a small gap stops every force
- No, a magnet can pull across a small gap without touching

Corrigé

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Touch it or not: contact and non-contact forces W1-mt_lcf8lx-LkZ-s1

Non-contact force · Magnetism can act at a distance, so it is a non-contact force.
Faux · Your foot has to touch the ball to kick it, so kicking is a contact force.
A non-contact force, because the pull happened before they touched · The button started moving before anything touched it, so the pull worked across a gap. That makes it a non-contact force.
Contact force · A contact force only works when the two objects are touching, like a push or a pull.
2 · Only the two magnet forces work without touching, so 2 of the 6 forces are non-contact forces.
It needs no touching · A non-contact force is one that works without touching. Gravity does it too, so it is not only magnets.
Pushing a swing · Pushing needs your hand to touch the swing, so it is a contact force.
Faux · A magnet can pull metal from a short distance away, without touching it.
Two, the push and the rubbing · The push needs his hands touching the box, and the rubbing friction needs the box touching the floor. Both are contact forces, so there are 2.
No, a magnet can pull across a small gap without touching · A magnet can pull a paperclip across a small gap, so a force can happen even when the two things are not touching.