Forces

Question 1

What is a scalar and vector quantity?

Answer 1

A scalar only has magnitude

A vector has magnitude and direction. Force is a vector quantity

Question 2

What is a contact force and give examples?

Answer 2

objects are actually touching. E.G friction,tension,air resistence,upthrust

Question 3

What is a non contact force and give examples?

Answer 3

Objects are not touching. E.G gravitonal force,electrostatic force ,magnetic force

Question 4

What is gravity?

Answer 4

force of attraction between all mases
Mass is the amount of matter it contains and is constant
Weight is the force acting on an object due to gravity
Weight= mass x gravitational field strength (W=mg)

Question 5

What is resultant force?

Answer 5

More then one force is acting on an object and they can be replaced with a single force which has the same effect
Force = Mass x Acceleration
F=ma

Question 6

How is work done?

Answer 6

when a force causes an object to move ,work is done on the object
when work is done, energy transfers takes place within the system.

Question 7

What is the difference between elastically/inelastically deformed?

Answer 7

elastically deformed=object returns to it original shape after the force is removed.
Inelastically deformed=objects does NOT return to its original shape

Question 8

What happens once the limit of proportionality has been exceeded\?

Answer 8

Once the limit of proportionality has been exceeded doubling the force will no longer double the extension the relationship will become non-linear and curved
Force= spring constant x extension
F=ke

Question 9

What happens to the particles in a fluid?

Answer 9

fluid is either fluid or gas

When particles move around in a container they collide and these collisions create a force to the surface.

Question 10

What happens if there is a low atmospheric pressure?

Answer 10

greater the altitude ,the less dense the atmosphere lower the atmospheric pressure

Question 11

What does pressure at a particular point in a column of liquid depend on?

Answer 11

height of the column above the point

density of liquid

Question 12

Describe upthrust

Answer 12

the bottom surface has a higher pressure and creates a resultant force upwards
The upwards force exerted by a fluid on a submerged object is called up thrust

Question 13

What is Distance?

Answer 13

Scalar quantity
how far an object moves
it does not take into account the direction

Question 14

What is displacement?

Answer 14

Vector quantity
has magnitude this describes how far the object has travelled from the origin
it also has direction

Question 15

What is speed?

Answer 15

measurement of how fast an object travels

scalar quantity

Question 16

What is velcoity?

Answer 16

Vector quantity

when travelling in a straight line an object with constant speed also has constant velocity

Question 17

What is a Distance-time graph used for?

Answer 17

used to represent the motion of an object travelling in a straight line
If an object accelerates the line will be a curve

Question 18

What is velocity time graph used for?

Answer 18

used to find the acceleration of an object

Question 19

How does an object accelerate when it falls through a fluid?

Answer 19

when an object falls through a fluid
objects accelerate due to the force of gravity
as it speeds up the resistive force increase

Question 20

Do all object have momentum?

Answer 20

all moving objects have momentum but if it is not moving the momentum is 0

Question 21

What is conservation of momentum?

Answer 21

In a closed system the total momentum before an event is equal to the total momentum after the event

Question 22

conservation of momentum example

Answer 22

two cars travel at the same direction along a road.Car A collides with the back of car Calculate the velocity
of the car after the collision

momentum before collision-momentum A + momentum B
(mass A x velocity a) + (mass B x velocity of B)
(1200 x 20)+(1000 x 9)
24000 + 9000=33000kg m/s

momentum after collision=33,000kg m/s
momentum after collision = (mass A + mass B) x ( new velocity combined)
(1200 + 1000)=2200
33000/2200=15m/s

Question 23

centre of mass

Answer 23

The single point through which the weight of the object can be said to act.

Question 24

What do vector diagram show?

Answer 24

used to show the overall effect when more then one force acts on an object
OR can be used to show when a force is acting in a diagonal direction

Question 25

How do you draw a vector diagram?

Answer 25

forces are added together to find a single resultant force including both magnitude and direction vectors are added heat to tail and arrows are drawn

Question 26

How do you draw a diagonal vector diagram?

Answer 26

diagonal line (FR)can be broken down to F1 and F2 F1 is the same length of FR in the horizontal direction F2 is the same length of FR in the vertical direction

Question 27

Give an example of work done?

Answer 27

E.G work done to overcome friction causes an increase in heat energy. Work done= Force x distance W=fs 1 joule=1 Newton Metre

Question 28

Is extension directly proportional?

Answer 28

Extension of an elastic object is directly proportional to the applied force

Question 29

What happens if the spring constant is high?

Answer 29

higher spring constant, stiffer the string amount of work done and energy store is equal SPRINGS DO NOT GO PAST THE LIMIT OF PORPORTIONALITY.

Question 30

What happens of the pressure acts on a large area?

Answer 30

If the pressure act on a bigger area it will produce a larger force

Question 31

When is there less air above the surface?

Answer 31

At a high altitude there is less air above a surface than at lower altitudes so there is a smaller weight acting on the surface

Question 32

What does it mean if the column is high and the liquid is dense?

Answer 32

greater the pressure greater the weight above the point greater the force on the surface at that point

Question 33

In terms of upthrust what happens when an object is less dense that the liquid?

Answer 33

*displaces volume of liquid greater than its own weight so it will rise to the surface *will float with some of the object remaining below the surface

Question 34

How does an object sink or float?

Answer 34

If an object has a low density more of the object will remain above the surface An object denser then its surrounding can not displace enough liquid to equal its weight so it will sink

Question 35

When does an object sink or float?

Answer 35

An object floats when its weight is equal to upthrust and sinks when the weight is greater then upthrust

Question 36

What factors affects speed?

Answer 36

Factors like age,fitness,distance affects the person who is walking,running,cycling

Question 37

What happens if an object does not travel in a straight lien?

Answer 37

*the speed will be constant but the velocity will change as the direction changes

Question 38

What happens if an object is moving in a circle?

Answer 38

* the direction is constantly changing so it constantly changing velocity * it is accelerating even if it travelling at a constant speed

Question 39

What happens when resultant force reaches 0 in terminal velocity?

Answer 39

resultant force reaches zero when the resistive forces balance the force of gravity. At this point the object will fall at a steady speed and its called terminal velocity