Forces In Equilibrium

Question 1

What is centre of mass?

Answer 1

The point through which a single force on the body has no turning effect

Question 2

What is the principle of moments

Answer 2

for an object in equilibrium Sum of clockwise moments=Sum of anti clockwise around any point

Question 3

What are the two conditions of equilibrium on a body

Answer 3

Resultant force must be 0N

Principle of moments must apply

Question 4

what is a vector

Answer 4

physical quantity with direction and magnitude

Question 5

what is a scalar

Answer 5

physical quantity with magnitude only

Question 6

how do you find the angle between displacement vectors and resultant vector

Answer 6

either scale diagram and protractor
or
Pythagoras theorem and tan=opp/adj

Question 7

how do find the resultant force and the angle between two force vectors at right angle to each other

Answer 7

force= (F1+F2)^1/2
angle= tan=F1/F2

Question 8

define a moment

Answer 8

moment= force x perpendicular distance between line of action and the pivot point

Question 9

what does a closed vector triangle mean

Answer 9

an object is in equilibrium

Question 10

what is a couple

Answer 10

pair of equal and opposite forces that act on a body

but not along the same line

Question 11

what will a body do if it is in stable equilbirum

Answer 11

if it is displaced then released

it returns to its equilibrium position

Question 12

what will a body do if it is in unstable equilibrium

Answer 12

if it is displaced then released

it will not return to its equilbirum