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What is distance?
Distance is how far places are from each other
What is displacement?
Displacement is the straight-line distance between the finishing and starting points
What is speed?
Speed is the measure how fast something moves
What is average speed?
Average speed is how fast something moves overall
What is instantaneous speed?
Instantaneous speed is speed at a particle instant
List ways speed can be measured.
- Light gates are used to time sporting events such as downhill skiing
- Motion sensor sends out pulses of radiation such as ultra sonic sound waves, which is reflected and provides data about its position and speed
- A ticker timer is used to measure speed. Further apart the dots the faster object moves
What is reaction time? What can slow it down?
- Reaction time is known as the time it takes for someone to react in a situation. Distractions slow it down, it can be caused by talking, texting or tuning the radio
- Age, fatigue and drugs can influence reaction time
How do you convert units?
- To convert km/h into m/s you ÷ 3.6
- To convert m/s into km/h you × 3.6
How do you calculate average speed?
- Average speed =Distance travelled
- Time taken
What is acceleration? What is it measured in?
- Is the rate at which something changes speeds and how quickly the change occurs
- Units are m/s2
What is acceleration due to gravity?
Acceleration due to gravity is 9.8 m/s2 for every second it falls
What is air resistance?
Friction between air and a falling body is air resistance
What can humans tolerate better? Vertical or horizontal drops?
- Humans can tolerate horizontal accelerations better than vertical accelerations
- Vertical drops are dangerous because blood flow to the brain can be disrupted which can cause unconsciousness or death
What is a distance-time graph?
- Shows how far an object travels as time progresses
- Flat line means stop
- Steep slope means object has covered great distance than a less steep slope
- The gradient (slope) is used to calculate average speed
What is a displacement-time graph?
Shows how the position of an object changes compared to where it started
What is a speed-time graph?
- Shows how an objects speed changes over time
- Flat line means constant speed
- Steep line upwards means acceleration
- Sleep line down means declaration
What is Newtons first law of motion?
An object at rest will remain so unless it is acted upon by a force, an object that is moving will continue to move at the same speed and in the same direction unless an unbalanced force acts upon it
What is an example of Newtons first law?
An example is when you are in train, you move along with its motion, however when an unbalanced force such as the breaks acts upon the train, it disturbs the initial motion, thus moving you forwards
What is inertia?
The tendency to resist any change in motion is called an objects inertia
What is Newtons second law of motion?
- A larger force is needed to accelerate a heavy load than a light load, a larger force is required to make something accelerate at a faster rate
- If you want to push a truck, you can do it yourself
What is Newtons third law of motion?
- For every action force there is an equal and opposite reaction force
- If you fire a gun, you move backwards
- If a nail is hit by a hammer, the nail exerts an equal amount of force back on the hammer
What is Newtons first law in relation to space?
- Space has no air so there is no air resistance to slow down a space craft
- A spacecraft continues to travel through space long after its fuel is gone
- Its inertia ensures it will keep travelling
What is Newtons second law in relation to space?
- According to Newtons second law, to launch a rocket, an enormous mass requires an equally enormous force
- As it rises, it experiences less resistance because gravity decreases
- Less fuel makes the rocket lighter, the fuel tanks are thrown away, which makes it light
What is Newtons third law in relation to space?
- Newtons third law states that the action force is the expulsion of gases
- The reaction force pushes the rocket in the opposite direction
What is energy changes?
Energy is need to make things happen. It includes kinetic, sound, light, heat and electrical. Energy can be transferred between two objects or it can be transformed from one form to another
What is kinetic energy?
- It is the energy of a moving object
- Amount of energy depends on mass and speed of an object
- Mass doubles = Energy doubles
- Speed doubles= 4 times Energy
What is potential energy?
- Energy that an object has because of its position and structure
- Gives objects the capacity to make things happen
- Example is foods contain chemicals that have energy in their chemical bonds
What is elastic potential energy?
- Energy stored in a stretched or compressed material such as a spring or elastic band
- This energy is converted into kinetic energy when this spring is released and returns to its original shape
What is gravitational potential energy?
- Potential energy possessed by an object due to its position above the ground
- Higher above ground more GPE, closer to ground less GPE
- Greater mass, greater GPE
What is the law of conservation of energy?
Energy may be transferred from one object to another, but it never created or destroyed
What is energy efficiency? What is it measured by?
- Energy can be lost into non useful forms such as heat and sound
- The efficiency is the measure of how much useful energy is produced
- Efficiency = Useful energy ×100%
- Total energy
How do you calculate average velocity?
- Average velocity: displacement
How do you calculate acceleration?
- Acceleration: final velocity– initial velocity
- Time taken
- A= v-u
How do you calculate acceleration due to gravity?
- Acceleration due to gravity: X= ut+1 at2
- Note that ‘a’ is always 9.8 m/s2
How do you calculate final speed?
- Final speed: initial velocity + (acceleration × time taken)
- V= u + at
How do you calculate netforce?
- Net force = mass × acceleration
- f= m × a
How do you calculate gravitational potential energy?
- GPE= mass × acceleration × height
- GPE= mgh
- Note that ‘a’ is 9.8 m/s2