section 4 - forces and energy

Question 1

what happens when a system changes

Answer 1

energy can be transferred into or out of the system

Question 2

what happens when a force moves an object through a distance

Answer 2

work is done on the object and energy is transferred mechanically
energy also often dissipates to the surroundings making the process less efficient

Question 3

what is power

Answer 3

• the rate of energy transfer

* how much work is being done per second

Question 4

what is the force that acts between all touching objects

Answer 4

normal contact force

Question 5

newtons 3rd law

Answer 5

when 2 objects interact, they each feel an equal but opposite force

• this is an interaction pair and can be represented with two arrows

Question 6

what is a moment

Answer 6

the turning effect of a force

Question 7

how do you get the maximum moment

Answer 7

• increase force
• increase distance from the pivot
• push perpendicular to the spanner/object

Question 8

what does the principle of moments state

Answer 8

for an object in equilibrium,

the sum of the clockwise moments = the sum of the anticlockwise moments

Question 9

how does the size of the gear affect the size of the moment

Answer 9

• small gear = small moment

* in larger gears, the force is applied further from the pivot

Question 10

how can you work out how the speeds and moments change between interlocked gears

Answer 10

put the number of teeth on each gear into a ratio