chap 6 revision practice Q's

Question 1

Answer 1

Question 2

Answer 2

question is trying to make the weight whitch act’s on the middle of the tray to look like a support force

w= 1.1772
dx= 0.25
D=0.1
Sy = Q =2.94
P = Q - w = 1.76

SyD=Wdx

Question 3

Answer 3

Question 4

what should you do if you finished early

Answer 4

check units

Question 5

what formula about moments you should remember

Answer 5

SyD = Wdx

Question 6

what must force always be

Answer 6

Newtons

Question 7

what do you do if force is not given perpendicular to line of action

Answer 7

Question 8

what are the units to moment typically and what could they be given as

Answer 8

typically Nm but can be given as Ncm

Question 9

what can you tell me about this image

Answer 9

• 2 arrows F1 and F3 are going anticlockwise and 1 arrow F2 clockwise is going clockwise therefore (F2 * D2) = (F1 * D1 + F3 * D3)

Question 10

A couple consists of a pair of forces that are:

Answer 10

• Equal in magnitude
• Opposite in direction
• Perpendicular to the distance between them

Question 11

what do couple forces equal to and why

Answer 11

Question 12

Answer 12

• alsong as the two forces where also not sharing the same line of action (not directrly aligned)

Question 13

what happens as the base get’s wide on an object

Answer 13

The wider base an object has, the lower its centre of mass and it is more stable vice versa

Question 14

what happens to center of mass in gravitational field

Answer 14

major points
* uniform gravitational field (beware, read pic)
* Since weight = mass × acceleration due to gravity, the centre of gravity does depend on the gravitational field (you can split up a formula into it’s component parts to figure stuff like this out)
* The centre of mass does not depend on the gravitational field

Question 15

when asked to work out whitch object is in equilibrium what helps

Answer 15

• It can help to not think of the object as rotating