chapter 8 - forces in balance

Question 1

what is scalar quantity?

Answer 1

a quantity that only has a size (magnitude) but has no direction

Question 2

what is a vector quantity?

Answer 2

a quantity that has both a size and direction

Question 3

what is a force?

Answer 3

a push or pull that acts on an object due to the interaction with another object

Question 4

is force a vector or scalar quantity?

Answer 4

a vector quantity, because it has a direction

Question 5

what is a contact force?

Answer 5

a force that arises when objects are physically touching (friction, air resistance, tension, normal contact force)

Question 6

what is a non-contact force?

Answer 6

a force that arises when objects are physically separated (gravitational, electrostatic, magnetic)

Question 7

whats the same about the interaction pair of forces when two objects interact with each other?

Answer 7

the forces are the same size

Question 8

whats different about the interaction pair of forces when two objects interact with each other?

Answer 8

the forces are in opposite directions

Question 9

size of resultant force on an object if the forces on it are balanced?

Answer 9

zero

Question 10

name of the force acting on an object due to gravity?

Answer 10

weight

Question 11

what instrument can be used to measure the weight of an object?

Answer 11

a newtonmeter

Question 12

what is the centre of mass?

Answer 12

the point through which the weight of an object can be considered to act

Question 13

what does newtons first law say?

Answer 13

the velocity of an object will only change if a resultant force is acting on it

Question 14

what is the resultant force on an object moving at a steady speed in a straight line?

Answer 14

zero

Question 15

what will an object experience if the resultant force on it is not zero?

Answer 15

an acceleration / change in velocity

Question 16

what does newtons third law say?

Answer 16

when two objects interact they exert equal and opposite forces on eachother

Question 17

what is scalar?

Answer 17

have a magnitude

Question 18

what is a vector?

Answer 18

has a magnitude and direction

Question 19

vectors VS scalars

Answer 19

vectors -

• velocity
• weight
• acceleration
• force
• gfs (gravitational field)

scalars -

• speed
• mass
• energy

Question 20

whats the equation linking force mass and acceleration?

Answer 20

F = M x A
force = mass x acceleration

Question 21

what is the centre of mass?

Answer 21

the point at which all mass is considered to act and therefore the point at which gravity is considered to act

Question 22

what is an irregular object?

Answer 22

• suspend object, draw a ijne straight down from the pivot, the COM will be somewhere on this line
• rotate object and repeat, where lines intersect is the COM