Section 1 - Motion ,Forces And Conservation Of Energy

Question 1

What’s the difference between speed and velocity ?

Answer 1

Speed- How fast an object is moving during a set time and it’s a scalar quantity

Velocity - direction is specified and it’s a vector quantity

Question 2

What’s gravity ?

Answer 2

The force of attraction between all masses

Question 3

What’s newton first law ?

Answer 3

If the resultant force on a stationary object is zero ,the object will remain stationary .
If the resultant force on a moving object is zero ,the object will continue moving at the same velocity.

Question 4

What’s newton second law?

Answer 4

The larger the resultant force acting on an object, the more it accelerates so force and acceleration are directly proportional . Acceleration is inversely proportional to the mass of the object
F = M×A

Question 5

What’s newton third law ?

Answer 5

When two forces interact, the forces they exert on each other are equal and opposite

Question 6

What’s the resultant force?

Answer 6

The sum of forces acting on an object.

Question 7

If the resultant force on a moving and stationary object is 0, what happen to the object?

Answer 7

• The moving object still moves at the same velocity .

- the stationary object stays that way .

Question 8

What happens if the resultant force on a stationary object is not 0?

Answer 8

It will accelerate in the same direction of the force .

Question 9

What happens if the resultant on moving object is not 0?

Answer 9

It will accelerate ,decelerate or change direction .

Question 10

If a ball is tied to a string and is spun around. What force is acting upon it ?

Answer 10

Centripetal force

Question 11

What’s the speed and velocity of a ball that’s tied to a string and spun around ?

Answer 11

The speed will remain the same and the velocity will change, therefore causing it to accelerate

Question 12

When a bucket of water is tied to a rope and spun around ,what force acts upon the bucket?

Answer 12

Tension force on the rope

Question 13

What’s acceleration?

Answer 13

The increasing change in velocity

A = v-u÷t

Question 14

What’s inertial mass ?

Answer 14

The ration of force over acceleration

M =F÷a

Question 15

When can an object only be in equilibrium?

Answer 15

When the weight of it is equal to the normal contact force

Question 16

Explain the interactions of forces when two skaters, staker(B) being heaver , push against each other .

Answer 16

When skater(A) push skater(B) , she feels an equal opposite force from skater(B)’s hand

• this is the normal contact force
• both skaters feel the same sized force in the opposite directions
• they then accelerate from each other
• skater(A) has a smaller mass , so will accelerate more than skater(B) a =F÷m

Question 17

What’s the difference between mass and weight?

Answer 17

Weight can change depending on the gravitational field strength whereas mass has the same value anywhere .

Question 18

What’s momentum define as ?

Answer 18

The product of the objects mass and velocity .

P= mass × velocity

Question 19

What’s momentum like in a closed system ?

Answer 19

The total momentum before an event is the same as after the event
-no momentum(energy) is lost or gained .

Question 20

What’s conservation of momentum ?

Answer 20

The total momentum before an event is the same as after the event.

Question 21

A red ball is stationary and a white ball is moving with a velocity. Explain the changes in momentum in the balls and in general as they collide. The balls are the same size and mass.

Answer 21

As the white ball has a velocity and a mass it has momentum

• white ball hits red ball causing it to move
• red ball has a momentum now (velocity and mass )
• white ball keep moving but at a smaller velocity so less momentum
• momentum of white and red ball has changed in the collision due to a change in velocities
• but the combined momentum of the red and white ball equals the original momentum of the white ball.

Question 22

What are the two main types of non renewable energy?

Answer 22

Fossil fuels

Nuclear fuels

Question 23

What are fossils fuel ?

Answer 23

Natural resources that form underground for million years and are typically burnt to provide energy .

Question 24

What are the three main fossil fuels?

Answer 24

Coal , gas , oil

Question 25

Why are fossils fuels and nuclear energy considered to reliable ?

Answer 25

There’s still plenty of fuel around to meet the current demand and power plants always have fuel in stock

Question 26

Why is it an advantage for fossil fuels and nuclear energy to be reliable?

Answer 26

They can respond quickly to changes in energy demand . They use more fuel to release more energy.

Question 27

What are two advantage of fossil fuels?

Answer 27

The cost to extract fossil fuels is low

-fossil fuel power plants are relatively cheap to build and run

Question 28

Why is nuclear power more expensive than fossil fuels ?

Answer 28

Because the power plants are more expensive to build and there are costs for safety decommission

Question 29

What’s the impending disadvantage of fossil fuels ?

Answer 29

• they are a finite resource
• as we are using more than is being produced
• so they are slowly running out

Question 30

What environmental problem do fossil fuels create?

Answer 30

They release carbon dioxide into the atmosphere when they are burnt. Which adds to the greenhouse effect and contributes to global warming .

Question 31

How do fossil fuels cause acid rain and how can it be prevent.

Answer 31

Burning coal and oil releases sulfur dioxide which cause acid rain . It can be reduced by taking sulfur out before the fuel is burned or by cleaning out the emissions .

Question 32

What environmental problem do oil spillage cause ?

Answer 32

It affects mammals and birds that live in and around the area .

Question 33

What are the dangers of nuclear power?

Answer 33

Although it’s clean ,nuclear waste is very dangerous and difficult to dispose of. There’s always a risk of a major catastrophe like the fukushima disaster in japan

Question 34

What are some examples of renewable energy sources ?

Answer 34

• Bio fuels
• wind
• solar
• hydro-electric
• tidal

Question 35

What’s is an advantage and disadavange about renewable energy?

Answer 35

Advantage is that they will never run out, so th3 energy can be renewed as it’s used .

-disadvantage is that they dont provide much energy and some of them are unreliable as they depend on the weather .

Question 36

What are biofuels and how are they used as an energy resource?

Answer 36

It’s a renewable energy resources that can be created from plants products or animals dung . They can be solid liquid or gas and can be burnt to produce electricity or run cars in the same way as fossil fuels .

Question 37

Why are bio fuels considered to be fairly reliable ?

Answer 37

Because crops take a relatively short time to grow and different crops can be grown all year round .

Question 38

What are the disadvantage of bio fuels ?

Answer 38

The cost to refine bio fuels is very high
-and some worry that growing crops specifically for bio fuels means there’s no enough space or water to meet the demands for crops that are grown for food.

Question 39

What’s an environmental disadvantage of bio fuels?

Answer 39

In some regions large areas of forest have been cleared to make room to grow bio fuels

• resulting in lots of species losing their natural habitats
• the decay or burning of vegetation also increases methane and CO2 emissions .