Speed Distance Time Units Distance metres m Time

Speed, Distance & Time Units: Distance = metres (m) Time = seconds (s) Speed = metres per second (m/s) Distance-Time Graphs Acceleration Calculating speed Speed and velocity are similar, but not the same. They are both measured in metres per second (m/s), but velocity always has a direction. A horizontal line on a distance-time graph means the object is travelling at constant speed. The gradient of a distance-time graph tells you the speed. • A steep gradient means a high, constant speed (C – D) • A shallow gradient means a low, constant speed. (E – F) • A horizontal line means the object has stopped moving. (B – C) (D – E) Investigating Speed To measure speed you need to measure the distance that an object has travelled, and the time it has taken to travel that distance. Method: 1. Stick a card to the top of the trolley for the light gates to measure, measure the length of the card. 2. Increase the slope of the ramp until the trolley just rolls by itself 3. Connect two light gates to a data logger 4. Hang a 1 N weight from the end of the string 5. Release the trolley. The light gates will record the time it takes for the card to pass through, so that you can calculate speed. 6. Repeat with more hanging weights to change the force. This is where you can change weight (force) The more force you add to the trolley, the faster its speed will be. The acceleration of an object is a measure of how quickly its velocity changes. Speed-Time Graphs The gradient of a speed-time graph tells you the acceleration. • An upwards gradient means the object is accelerating (A–B) (D-F) • A downwards gradient means the object is decelerating (E-F) • A horizontal line means the object is moving at a constant speed (B – C) (D – E) All waves can carry information and energy but not matter. Waves In water waves it is always the wave which is moving, the water molecule never moves. In a sound wave, it is the wave that moves not the air particle. Wave terminology Period – length of time it takes one wave to pass a given point Wavelength – distance from one point of wave to the same point on the next wave Amplitude – maximum distance from rest position Velocity – speed of the wave it travels in Wave speed (m/s) = Frequency (hz) x wavelength (m) Waves can change direction when they move into a different medium. This is called refraction.

The Electromagnetic Spectrum The Eye & Light All electromagnetic waves are transverse and travel at the speed of light in a vacuum. Visible light is the of the electrom only part agnetic spectrum that we can see. light: Red, Order of colours in visible Indigo, ue, , Bl een , Gr Orange, Yellow Violet (ROYGBIV) • • From radio waves to gamma rays the frequency of the waves increase and the wavelengths get shorter. As the frequency increase so does the energy of the waves. My name is Hershel and I split white light with a prism and then measured the temperature of all the colours. Red was hottest but beyond read was even hotter! I discovered infrared My name is Ritter and I split the light like Hershel but instead of thermometers I looked at how fast the light caused silver chloride to react. Violet was fastest but just past violet was even faster. I discovered ultraviolet! Pressure = force ÷ area • A given force acting over a BIG area means a SMALL pressure. • A given force acting over a SMALL area means a BIG pressure. EXAMPLE: If you swing round on one leg of a chair, you put four times as much pressure on one point of the floor as you do if you sit properly. This is because four chair legs spread the pressure over four times more area than one chair leg can. LIQUID GAS You can’t increase the pressure of a solid, because it’s particles are already closely packed together. Liquids can be compressed slightly, as the particles can get closer, and gases can be put under a lot of pressure because the particles are far apart. The higher you go above sea level, for example up a mountain, the lower the air pressure because there is less atmosphere above you. description function Cornea Front part of the tough outer coat. It is transparent. refracts light - bends it as it enters the eye Iris Pigmented - decides the colour of your eyes - so light cannot pass through. Its muscles contract and relax to alter the size of its central hole or pupil. controls how much light enters the pupil Lens Transparent, flexible disc behind the iris attached to the ciliary muscles. focuses light onto the retina Retina The lining of the back of contains the eye. light receptors Optic nerve Bundle of sensory carries neurones at back of eye. information from the eye to the brain Conduction & Convection The units of pressure are Pascals (Pa). 1 Newton / metre 2 = 1 Pascal SOLID part The deeper you go in the ocean, the higher the pressure. This is because there is more water above you. Conduction, convection and radiation are all ways that heat can be transferred. Conduction is the flow of heat from one solid to another. When solid particles heat up, they vibrate more quickly. This causes the particles next to them to start to vibrate more quickly. This spreads throughout the solid causing it to heat up. Radiation is a form of heat transfer that doesn’t need contact between the heat source and the object eg. The Sun heating the Earth. Light coloured objects absorb and emit radiation much more slowly than dark coloured objects. Convection is the movement of particles (in liquids and gases) away from a heat source to form currents. Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. The liquid or gas in hot areas is less dense than the liquid or gas in cold areas, so it rises into the cold areas. The denser cold liquid or gas falls into the warm areas. In this way, convection currents that transfer heat from place to place are set up.