P9

Question 1

different ways objects can interact

Answer 1

-at a distance without contact(gravitational, electrostatic and magnetic fields)
-by contance with friction and normal contact forces
-producing pairs of forces represented as vectors

Question 2

vector and scalar quantitiues

Answer 2

vector-magnitude and direction

Question 3

practise

Answer 3

vector, free body and work out and explain resultant forces and moveemnt in response to that

Question 4

situations where forces can cause rotation

Answer 4

doors on hinges
by applying force
door will turn on its hinges
turning effect of the force causes the object to rotate

Question 5

moment(N m)=

Answer 5

force x distance normal to the direction of the force

Question 6

principle of moments

Answer 6

where rotational forces are in equilibrium:
sum of clockwise moments=sum of anti-clockwise moments
for rotational forces in equilibrium

Question 7

how leavers and gears transmit rotational effects of forces

Answer 7

levers-
an effort is applied to one end to rotate one end about the pivot
the opposite end is also rotated about the pivot in the same direction=effect of rotating or lifting the load
make use of moments act upon heavier object with a larger force
gears-
have teeth and rotate on an axle or shaft
teeth of one gear fit into the teeth of another
lets one gear turn the other meaning ine axle or shaft can tur another
where the gear mets the other gear must turen in the same dirvcetionmeans gears rotate in opposite directions
force acting on both gears are identicla but moments are different
if the driven gear is made larger it will rotate slower but with a bigger moment (low gear ratio) and vice versa for smaller driven gear

Question 8

how do reduce unwanted energy transfers

Answer 8

lubrication-reduces dfriction which transfers heat energy from the system into the surroundings