Forces Revision

Question 1

What three forces slow objects down?

Answer 1

Friction , air resistance and water resistance act between moving surfaces to slow objects

Question 2

What do most forces require?

Answer 2

Direct contact

Question 3

What does friction do to objects?

Answer 3

It grips them

Question 4

Why do objects stop when being pushed along a surface?

Answer 4

Because the rough surfaces can no longer move past each other.

Question 5

The rougher the surface….

Answer 5

The more the friction

Question 6

Explain contact forces

Answer 6

They are forces that act when the objects are in contact

Question 7

Explain noncontact forces

Answer 7

They are forces that act when the objects are not in contact(magnetism)

Question 8

What is a drag force?

Answer 8

A Force that slows down an object moving through fluid, such as air or waIter is called a drag force.
Eg(water resistance and air resistance)

Question 9

Describe the particles behind the drag force

Answer 9

In air the particles are more widely spaced so the solid moves through easier ,compared to in a liquid where the particles are touching ,the solid has less space to move through the water particles,which slows the object down.
The opposing force (in this case travelling backward is drag force )

Question 10

What affects motion?

Answer 10

Drag forces and friction affect motion

Question 11

Laura measures the speed of a ping-pong ball when she drops it from different heights using a motion sensor .She notices that the speed of the ping-pong ball is roughly the same at the end of it’s fall for every drop higher than 260 cm explain why the final speed of the ball does not change after 260 cm.

Answer 11

As the ball falls the air resistance increases,for heights above 260 cm both of the opposite forces become balanced so the ball moves at a constant speed.

Question 12

What does it mean when the resultant force is zero?

Answer 12

it means that the object is either in equilibrium or moves at a constant speed

Question 13

How can you reduce drag forces and friction?

Answer 13

You can reduce drag friction by …

1. )making shapes more streamlined
2. )decreases the surface area
3. )lubricating objects

Question 14

What is it called when forces change the shape of objects?

Answer 14

Deformation

Question 15

What does it cause when forces squash an object?

Answer 15

Compression

Question 16

What does it cause when forces stretch an object?

Answer 16

Tension

Question 17

What happens to the bonds when you squash a solid object or exert a force on an object?

Answer 17

The bonds are compressed

Question 18

What are bonds?

Answer 18

Bonds are particles joined strongly together

Question 19

What is a support force from a chair or the floor called?

Answer 19

A reaction Force

Question 20

What is a reaction Force?

Answer 20

A reaction force is a force acting in the opposite direction.
Eg(air resistance,and gravity for ,rock falling)

Question 21

The amount that things like cords and springs stretch is called the….

Answer 21

Extension

Question 22

What can Forces can make objects change ?

Answer 22

the shape speed or their direction when they are in motion they can also make objects change shape.

Question 23

What can stretching forces do?how does this effect the object?

Answer 23

They can change the shapes .it makes the object longer and thinner .

Question 24

What do compression forces do?

Answer 24

They squash objects,making them smaller.

Question 25

What is a plastic material?

Answer 25

It is a materiel that changes shape PERMANENTLY,when they are deformed from an external force.
(Eg:play dough )

Question 26

What is an elastic material?

Answer 26

It is a material that returns to its original shape ,once the external force is re,over.
(Eg:elastic band)

Question 27

Hooke’s Law is…

Answer 27

That the force is extension is directly proportional to the force applied .

Question 28

Hooke’s law’s equation is…

Answer 28

F=kx

Question 29

F=?
k=?
x=?

Answer 29

F=force (N)
K= spring constant (n/m)
X=the extension (m)

Question 30

What is the spring constant ?

Answer 30

It is hbmnviyfkhvmbvkhotofindout@school

Question 31

The ? The area the ? The pressure

Answer 31

The smaller the area ,the more the higher the pressure

Question 32

The force spread over a ? Area produces a ? Pressure

Answer 32

The forces spread over a larger area produces a lower pressure

Question 33

What is the equation for calculating pressure ?

Answer 33

Force=pressure x area (measured in n/square meter or centimetre)

Question 34

What are the 4 steps for calculating equations?

Answer 34

1.) write out the formula
2.)substitute in the values
3.)calculate the answer
4.)add unit
FOLLOW ALL STEPS IN ORDER!

Question 35

KEY POINT:

Answer 35

When asked to explain results ,think about the particles.

Question 36

G=…

Answer 36

Gravitational force field

10g on earth

Question 37

What is a gravitational force field?(measured in g/10g on earth)

Answer 37

Where mass experiences a force

Question 38

Weight =

Answer 38

Mass x g(gravitational force field )
Eg:
m=10kg
W=100N

Question 39

Weight is …

Answer 39

A FORCE measured in Newton’s

Question 40

Mass is …

Answer 40

How much stuff something is made of (measured in grams or kilograms)

Question 41

The ? Of liquids is ?Around the ? Of a container

Answer 41

The pressure of liquid is all around the walls of the container

Question 42

Pressure actins in…

Answer 42

All directions

Question 43

What does pressure increase with?

Answer 43

It increases with depth

Question 44

Why do boats sink?

Answer 44

1. )(The boat is less dense than the water )
2. )many of the particles contain air
3. )up thrust

Question 45

Higher….(particles)

Answer 45

Less particles