UNIT 1 - Basic Physics

Question 1

Define scalar quantity

Answer 1

Scalar quantity only has magnitude

Question 2

Define vector quantity

Answer 2

Vector quantity has both magnitude and direction

Question 3

Name 8 scalar quantities

Answer 3

Distance
Speed
Mass
Energy
Volume
Area
Pressure
Density

Question 4

Name 6 vector quantities

Answer 4

Displacement
Velocity
Force
Acceleration
Momentum
Electric current

Question 5

How do u resolve vectors?

Answer 5

Trigonometry aka soh cah toa

Whichever sides of triangle u got u use to do sohcahtoa, so if u got adjacent and opposite u do toa, tan

Question 6

How to resolve vectors into components

Answer 6

Horizontal is zcos(angle)
Verticle is zsin(angle)

Its just reversing resolving vectors ig

Question 7

Equation for weight, w?

Answer 7

W=mg
Weight = Mass x gravity

(Gravity on earth = 9.81N)

Question 8

What is equation for density

Answer 8

P = m/v

density = mass/volume

Question 9

Define density

Answer 9

Measurement of how tightly a material is packed together, defined as the mass per unit volume. P= m/v

Question 10

Unit for density

Answer 10

Kgm⁻³ or kg/m³

or for smaller units gcm⁻³

Question 11

Define centre of gravity

Answer 11

The single point within a body at which the entire weight of the body may be considered to act

Question 12

Define centre of mass

Answer 12

Point where the total mass of an object can be treated as a single point

Question 13

What is the condition for the two positions of CoG and CoM to coincide?

Answer 13

CoG based on weight, CoM based on mass. So when the gravitational field across an object is uniform, the two are identical.

(Uniform meaning the same across the object i think)

Question 14

At what point will an object tip over?

Answer 14

When the centre of GRAVITY passes the pivot

Question 15

Define moment of force (about a point..?)

Answer 15

The moment of a force about a point is defined as the force x the perpendicular distance from the point to the line of action of the force

i.e (moment = force x distance)

Question 16

How can u increase size of the moment

Answer 16

a) increase size of force

b) increase perpendicular distance between force and pivot

(This refers to the definition and equation m=fxd so common sense)

Question 17

What is equation of moments (include units)

Answer 17

Moment(Nm) = force(N) x perpendicular distance from pivot(m)

m = F x D

Question 18

What is the name given to the turning effect of a force

Answer 18

Moment (torque)

Question 19

Define principle of moments

Answer 19

For a system to be in equilibrium,

the sum of anticlockwise moments about a point = the sum of clockwise moments about the same point

Question 20

When is a body said to be in equilibrium?

Answer 20

When theres no resultant force and no net movement

Question 21

Unit for force?

Answer 21

Newtons N

(N=kgms⁻²)