What is a FORCE FORCE Push or Pull

What is a FORCE?

FORCE Push or Pull

Forces have… Size & Direction

Unit of Force NEWTON

All forces are exerted by one object on another object.

Does force always result in motion? NOT always Stay tuned for more on this topic. .

Magic or Just Plain Science? Force – magician’s weight; is large because there are hundreds or even thousands of nails. Pressure – amount of force exerted on a given area; from each nail is not enough to break the magician’s skin. Force is spread over a wide area to reduce pressure.

Net Force that results from combining all forces exerted on an object.

Forces in Combination This combining may involve adding (same direction) or subtracting (different directions) the forces.

Move that bus, I mean piano! • TB pg. 116 Figure 8 • What would happen if the forces were in opposite directions (both pushing on the piano)? The piano would move from left to right because the girl is exerting a force 5 N greater than the force the boy is exerting. Girl power!!!

It’s a dog’s life… • TB pg. 117 Figure 9

Read all about it… TB pg. 135

London Bridge is falling down, falling down… Try this Lean toward each other with palms touching. Back up as far as possible without falling. Now try this one. Feet together; hold hands. Lean back as far as possible without falling.

Did you feel the… • tension? • compression? • gravity? • friction?

This physical science stuff… is tension/compression on the brain !

It all comes crashing down tomorrow… Hope that’s not a reference to that Holt Anthology of Science Fiction again! really, it’s in the cards with balanced & unbalanced forces.

balanced, unbalanced, balanced, unbalanced balanced, unbalanced, unbalanced

• How does it all “pan” out? Balanced • Unbalanced – when all forces applied to an object result in net force of zero; – will not cause a nonmoving object to start moving; – will not cause a change in the motion of a moving object. – when net force is NOT zero; – result in motion; – cause a change in motion (acceleration); – NOTE: an object can continue to move even after the unbalanced forces are removed.

Try your “hand” at this balancing act.