Section 1 - Motion ,Forces And Conservation Of Energy Flashcards
What’s the difference between speed and velocity ?
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
What’s gravity ?
The force of attraction between all masses
What’s newton first law ?
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.
What’s newton second law?
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
What’s newton third law ?
When two forces interact, the forces they exert on each other are equal and opposite
What’s the resultant force?
The sum of forces acting on an object.
If the resultant force on a moving and stationary object is 0, what happen to the object?
- The moving object still moves at the same velocity .
- the stationary object stays that way .
What happens if the resultant force on a stationary object is not 0?
It will accelerate in the same direction of the force .
What happens if the resultant on moving object is not 0?
It will accelerate ,decelerate or change direction .
If a ball is tied to a string and is spun around. What force is acting upon it ?
Centripetal force
What’s the speed and velocity of a ball that’s tied to a string and spun around ?
The speed will remain the same and the velocity will change, therefore causing it to accelerate
When a bucket of water is tied to a rope and spun around ,what force acts upon the bucket?
Tension force on the rope
What’s acceleration?
The increasing change in velocity
A = v-u÷t
What’s inertial mass ?
The ration of force over acceleration
M =F÷a
When can an object only be in equilibrium?
When the weight of it is equal to the normal contact force
Explain the interactions of forces when two skaters, staker(B) being heaver , push against each other .
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
What’s the difference between mass and weight?
Weight can change depending on the gravitational field strength whereas mass has the same value anywhere .
What’s momentum define as ?
The product of the objects mass and velocity .
P= mass × velocity
What’s momentum like in a closed system ?
The total momentum before an event is the same as after the event
-no momentum(energy) is lost or gained .
What’s conservation of momentum ?
The total momentum before an event is the same as after the event.
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.
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.
What are the two main types of non renewable energy?
Fossil fuels
Nuclear fuels
What are fossils fuel ?
Natural resources that form underground for million years and are typically burnt to provide energy .
What are the three main fossil fuels?
Coal , gas , oil
Why are fossils fuels and nuclear energy considered to reliable ?
There’s still plenty of fuel around to meet the current demand and power plants always have fuel in stock
Why is it an advantage for fossil fuels and nuclear energy to be reliable?
They can respond quickly to changes in energy demand . They use more fuel to release more energy.
What are two advantage of fossil fuels?
The cost to extract fossil fuels is low
-fossil fuel power plants are relatively cheap to build and run
Why is nuclear power more expensive than fossil fuels ?
Because the power plants are more expensive to build and there are costs for safety decommission
What’s the impending disadvantage of fossil fuels ?
- they are a finite resource
- as we are using more than is being produced
- so they are slowly running out
What environmental problem do fossil fuels create?
They release carbon dioxide into the atmosphere when they are burnt. Which adds to the greenhouse effect and contributes to global warming .
How do fossil fuels cause acid rain and how can it be prevent.
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 .
What environmental problem do oil spillage cause ?
It affects mammals and birds that live in and around the area .
What are the dangers of nuclear power?
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
What are some examples of renewable energy sources ?
- Bio fuels
- wind
- solar
- hydro-electric
- tidal
What’s is an advantage and disadavange about renewable energy?
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 .
What are biofuels and how are they used as an energy resource?
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 .
Why are bio fuels considered to be fairly reliable ?
Because crops take a relatively short time to grow and different crops can be grown all year round .
What are the disadvantage of bio fuels ?
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.
What’s an environmental disadvantage of bio fuels?
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 .
