Forces

Question 1

Object interaction

Answer 1

• Non-Contact - the objects are physically separated.
  o Electrostatic
   The charges cause a force of attraction/repulsion
  o Gravitationalattraction
   The mass creates a force of attraction
• Contact - the objects are physically touching
  o Normal contact force,which is felt in opposite direction to contact
   The force is normal to the planes of contact o Friction
   The surfaces and their roughness cause friction when moved in contact

Question 2

Resolutely force

Answer 2

This is a single force representing the sum of all the forces acting on an object
- If more than one force act along a straight line, the resultant can be found by adding (acting
in the same direction) or subtracting (acting in opposite directions) them

Question 3

Springs

Answer 3

To stretch, bend or compress an object, more than one force has to be applied
- If a single force is applied to an object, it will just move in that direction
o If it is pulled in opposite directions on either side of the object,it will stretch
o If It I s fixed at one point and stretched,a force is still being applied by the fixed point

Question 4

Newton’s first law

Answer 4

An object has a constant velocity unless acted on by a resultant force
- If a resultant force acts on the object, it will accelerate
o Acceleration is change in velocity overtime
o So the velocity will change
o Either the direction or speed of the object will change (orboth)
- If no resultant force acts on the object
o And the object is stationary,it will remain stationary
o And the object is moving,it will continue to move at the same velocity

Question 5

Newton’s third law

Answer 5

Whenever two objects interact, the forces they exert on each other are equal and opposite.
- Rocket taking off
o The rocket exerts a force on the gases being ejected.The gases apply a force equal
in magnitude but in opposite direction on the rocket, which lifts it off the surface.
- A book on a table
o The weight of the book(fromtheEarth)=the pull of the book on the Earth

Question 6

Conservation of momentum

Answer 6

• Momentum is always conserved in a collision or explosion (where there are no external forces

Question 7

Contact and non contact forces

Answer 7

Contact
Friction air resistance tension in ropes
Non contact
Magnetic force gravitational force electrostatic force