Mechanincs

Question 1

What are scalars?

Answer 1

Something that has magnitude (size) but not direction

Question 2

What are vectors?

Answer 2

Something that has magnitude and direction

Question 3

What is resolving a vector?

Answer 3

Splitting a vector up into it’s horizontal and vertical components

Question 4

How do you find its horizontal component?

Answer 4

horizontal component = hypontenous(resultent vector) * cosx

Question 5

How do you find its vertical component?

Answer 5

vertical component = hypontenous(resultent vector) * sinx

Question 6

What are the SUVAT equations?

Answer 6

v = u +at
s =(u+v)t /2
s=ut + (1/2)(at^2)
v^2 = u^2 +2aS

Question 7

What is “g”?

Answer 7

The acceleration due to gravity @ 9.81ms^-2
It can be used to replace “a”in SUVAT equations but should using be a negative number due to it acting downwards

Question 8

How do you calculate g?

Answer 8

Set up using
an electromagnet with a switch
a steel ball
trapdoor
Timer
computer

Measure the distance between the ball and the trapdoor
Flick the switch to make the steel ball fall
Make the switch also start the timer
Steel ball hits the trap door breaking the circuit and stopping the timer
Record the t
Repeat changing the height for 3 times
Use the rests to plot a graph for height against t^2
The gradient is the acceleration

Question 9

How would you reduce the uncertainty?

Answer 9

Use a computer to automatically drop the ball and start the timer
Have height to decrease the uncertainty

Question 10

Why do objects in projectile motion curve?

Answer 10

The horizontal and vertical motion must be thought of separately. Horizontal motion stays constant while vertical motion is affected by g

Question 11

What is a free-body force diagram?

Answer 11

Diagram that shows all forces acting on a single body

Question 12

What is newton’s first law?

Answer 12

The velocity of a object will stay constant (will not change) unless a resultant force acts on it.

Question 13

What is newton’s second law?

Answer 13

F = ma The acceleration is proportional to the force acting upon the object.

Question 14

What is newton’s 3rd law?

Answer 14

Every force has an equal and opposite reaction

If an object A exerts a force on an object B then object B exerts and equal but opposite force on object A

Question 15

What is fluid friction?

Answer 15

A.k.a drag
It increases with viscosity
It increases with the speed
it increases with surface area

Question 16

What is terminal velocity?

Answer 16

When the resultant force of an object is 0 due to frictional drag and the driving force is in equilibrium

Question 17

Terminal velocity (big mark question pls)?

Answer 17

An object accelerates from rest (either due to weight or driving force ect)
—-> increase in velocity
——->increase in the frictional forces
———–>reduction in resultant force
——————>resultant force of an object is 0 due to frictional drag and the driving force is in equilibrium

Question 18

What is momentum?

Answer 18

p = mv

Question 19

What is the main property of momentum?

Answer 19

Momentum is always conserved if no external forces are acting upon it

Question 20

How would you investigate momentum?

Answer 20

Air track (reduces friction) and light gates
Trolleys are pushed into each other
Light gates measure velocity of trolleys after they pass through them
Using the initial and final velocity you can find out the initial and final momentum of the trolleys

Question 21

What links force to momentum

Answer 21

f = ma
p = mv
——-> F = change in p/ change in t

Question 22

What is work done?

Answer 22

Force x parallel to the force Distance

Question 23

What do you do if the force is not parallel to the direction of motion?

Answer 23

Resolve the force and use the component that is parallel to the force

Question 24

What is power?

Answer 24

P = work done / time

Question 25

What is the principle of conservation of energy?

Answer 25

Energy cannot be created or destroyed, only transferred from one form to another

Question 26

What is efficiency?

Answer 26

useful energy output / total energy output

Question 27

What is the centre of gravity?

Answer 27

The single point in which it is considered that all the weight of an object acts through

Question 28

How does the centre of gravity relate to the stability of an object

Answer 28

The lower the centre of gravity the more stable the object would be.

Bigger base leads to more stability

Question 29

What is a moment?

Answer 29

moment = force * perpendicular distance from the line of action

Question 30

What assumption is made when using SUVAT?

Answer 30

Force and acceleration is constant

Question 31

What are the requirements for Newton’s 3rd law pairs?

Answer 31

The forces must be of the same type and equal magnitude
I push on wall and wall pushes on me (YES)
Gravity pulls on the book and the table pushes on the book (NO! different type of force)