unit 3 hard

Question 1

how to get the centre of mass of a thin material

Answer 1

suspend the shape from a point
attach plumb line to line of suspension
draw a line where the string rests
suspend from a second point and draw another line
where the 2 line cross = COM

Question 2

why an object falls

Answer 2

the line of action acting through the com is outside the base causing a resultant moment.

Question 3

how to make an object more stable

Answer 3

lower centre of mass and a wider base

Question 4

what is the unit for moments

Answer 4

Nm

Question 5

what is the unit for pressure

Answer 5

pascals

Question 6

how does a hydraulic system work

Answer 6

liquids are incompressable.
they exert equal force.
force exerted on one point is carried throughout the liquid and the force is multiplies or diminished depending on the area it is pushing.

Question 7

explain why a electromagnet is moved when arranged as a motor

Answer 7

electromagnet
magnetic fields interact
produce a resultant force

Question 8

what does a split ring commutator do

Answer 8

once the motor spins half way it reverses current direction and this reverses the force and keeps the object going in the same direction.

Question 9

how does induction work

Answer 9

an aternating potetnial difference in the iroin core causes a pd to be induced in the coils