Name: P2 Exam Date: Thursday 23 rd May P2 - Physics. Question Pack

Transcription

1 Name: P2 Exam Date: Thursday 23 rd May 2013 P2 - Physics Question Pack

2 P2 REVISION PART 1 MOTION Distance-Time Graphs The gradient of the line on a distance-time graph represents. The the gradient, the greater the speed. Using Graphs If an object is stationary, the line on a distance-time graph is. If an object is moving at a constant speed, the line on a distance-time graph is a straight line that slopes. Velocity & Acceleration Velocity-Time Graphs The gradient of the line on a velocity-time graph represents. The steeper the, the greater the acceleration. What does a horizontal line show on a velocity-time graph? Calculate the gradient of the line on a distance-time graph to give you the speed of an object. Calculate the gradient of the line on a velocity-time graph to give you the acceleration of an object. What area on a velocity-time graph shows the distance? If the value calculated for acceleration is negative, the body is decelerating slowing down. A deceleration is the same as a negative acceleration. velocity acceleration deceleration speed

3 P2 REVISION PART 1 MOTION Match the graph to the description of motion: distance-time graphs gradient speed velocity acceleration velocity-time graphs

4 P2 REVISION PART 2 FORCES Forces Between Objects Forces are measured in newtons, N. What is the rule with regard to forces? Resultant Force The resultant force is a single force that has the same effect as all the forces acting on an object. If an object is accelerating there must be a resultant force acting on it. If an object is accelerating what 3 things can it be doing? Stopping distance On The Road If a vehicle is travelling at a steady speed, the resultant force on it is. The driving forces are equal and opposite to the frictional forces. Distance travelled during the thinking distance, plus the distance it travels under the braking distance Force & Acceleration What always causes an acceleration? The bigger the resultant force on an object, the greater its. F = m x a Thinking distance Braking distance Is increased if the driver is tired or under the influence of or. Can be increased by: Poorly maintained roads Bad weather conditions. Condition of the car: eg: Worn Worn F is the resultant force in newtons, N. m is the mass in kilograms, kg a is the acceleration in m/s² Reaction time depends on the. Braking distance depends on the, and the condition of the vehicle. Acceleration is a change in velocity. An object can accelerate by changing its even if it is going at a. Therefore a is needed to make an object change. Force Newton mass

5 P2 REVISION PART 2 FORCES What is the definition of a force? What are balanced forces and when do they occur? Using the formula F=ma, fill in the table a b c d e Force (Newtons, N) Mass (kilograms, kg) Acceleration (meters/second squared, m/s 2 ) What are unbalanced forces and when do they occur? What is stopping distance, and what are the two parts that make up a car s stopping distance? Calculate the resultant force: What factors affect stopping distance? What do we do to prevent speeding in this country? What is terminal velocity? What is Hooke s law? force resultant force stopping distance thinking distance braking distance weight mass gravitation field strength drag force terminal velocity proportionality Hooke s law

6 P2 REVISION PART 2 FORCES Falling Objects The force of gravity is called An object acted on only by gravity will accelerate at about. F = m x a Where: F is the resultant force in newtons, N. m is the mass in kilograms, kg a is the acceleration in m/s² Becomes: W = m x g Where: W is the weight in newtons, N m is the mass in kilograms, kg g is the acceleration due to gravity in m/s² If an object falls through a fluid the fluid exerts a force on the object. Faster the object falls, the bigger the drag force becomes until it becomes equal to the weight of the object. Resultant force will then be. This is called. DON T FORGET: Mass is the amount of matter in an object. Weight is the force of gravity acting on it. Stretching & Squashing What does elastic mean? The extension of a spring is DIRECTLY PROPORTIONAL to the force applied to it, provided the limit of proportionality is not exceeded. How do we know that it is directly proportional? Extension is the difference between the length of the spring and its. Hooke s Law Equation: F = k x e Where F is the force applied in newtons, N k is the spring constant of the spring in newtons per metre, N/m e is the extension in metres, m What is the spring constant of a spring? gravitational drag force terminal velocity weight elastic proportionality Force & Speed Issues Reduces the speed of a vehicle reduces the amount of what? What is this called? Reducing air resistance, making a vehicle more also improves fuel economy. Speed cameras are used to discourage motorists from doing what? In pairs they can be used to calculate speed. What happens if you are caught speeding? When does skidding happen? What happens when you skid? surfaces are used to reduce or prevent skidding. How do these surface work? Where are they used?

7 P2 REVISION PART 3 WORK, ENERGY & MOMENTUM Energy & Work Work is done on an object when a force makes the object move. Energy transferred = work What is the unit for both work and energy? W = F x d Where: W is the work done in joules, J F is the force in newtons, N d is the distance moved in the direction of the force in metres, m Work done to overcome is transferred as energy that heats the objects that rub together and the surroundings. Explosions Momentum has both size and direction. One direction must be, therefore momentum in the opposite direction is negative. In an explosion the objects will move apart with and momentum. One being positive the other. So the total momentum after the explosion is. Gravitational Potential Energy Kinetic Energy The object will move apart with different speeds if they have. work friction kinetic energy elastic potential energy

8 P2 REVISION PART 3 WORK, ENERGY & MOMENTUM What is work done? What is the equation for work done? How does friction affect work done? What is momentum? Complete the question below using this equation momentum (kg m/s) = mass (kg) X velocity (m/s) If a sprinter with a mass of 50kg runs at a velocity of 10m/s what is their momentum? A 0.5 kg trolley is pushed at a velocity of 1.2 m/s into a stationary trolley with a mass of 1.5 kg. The two trolleys stick to each other after the impact. Calculate: The momentum of the 0.5 kg trolley before the collision The velocity of the two trolleys straight after the impact What is conservation of momentum and how do you calculate it? What features do we add to cars to make them safe? transfer work done gravitational potential energy elastic potential energy momentum conservation of momentum

9 P2 REVISION PART 3 WORK, ENERGY & MOMENTUM Impact Forces Car Safety When vehicles collide the force of the impact depends on what 3 things? When two vehicles collide they exert and forces on each other, also their total is unchanged. What is impact time? Cars today have several different safety features built into them, to reduce the forces on the occupants of the car in a collision. How do side impact bars, seat belts, air bags and crumple zones help with safety? Questions What can we use to find out the speed of a car before an impact? What is the unit of momentum? Where do you have crumple zones on a car and why? impact time crumple zone

10 P2 REVISION PART 4 CURRENT ELECTRICITY Electrical Charges If you rub two electrically insulating materials are rubbed together, are rubbed off one material and deposited on the other. Objects that have opposite electric charges each other, if they have the same electric charge they. Electric Circuits I is the current in amperes, A Q is the charge in coulombs, C t is the time in seconds, s. Every component has an agreed circuit symbol. Make sure you can recognise and draw them! Electric symbols Resistance Current is measured with an ammeter. Where are ammeters placed in relation to the component? What is the unit of current? The potential difference(pd) across a component is measured with a voltmeter. These are always placed in parallel with the component. What is the unit of potential difference? V is? W is? Q is? Don t forget units! R is? V is? I is? Don t forget units! Ohm s law: states that the current through a resistor at constant temperature is directly proportional to the potential difference across the resistor. insulating electron attract repel resistance series

11 P2 REVISION PART 4 CURRENT ELECTRICITY Label these circuit components: What is static electricity? What happens when you rub a polythene rod with a dry cloth? What happens when you rub a perspex rod with a dry cloth? You can use diagrams to help. Link the component to the correct graph What is resistance? What is the equation for resistance? What is the rule for resistance in a series circuit? What is the rule for resistance in a parallel circuit? static electricity protons neutrons ion electric current electrons coulombs (C) series potential difference volts (V) parallel resistance ohmic conductor

12 P2 REVISION PART 4 CURRENT ELECTRICITY Series Circuits How are the components connected in a series circuit? What happens if there is a break in the circuit? Is the current the same or different through each component? If you add together the potential difference what does it give you? Current-Potential Difference Graphs A current-potential difference graph for a resistor. The resistance of the individual components add up to give the total resistance of the circuit. A current-potential difference graph for a filament bulb, line is a curve so the current is not directly proportional to the. Parallel Circuits How are the components connected in a series circuit? What happens if there is a break in the circuit? Is the pd across each component the same or different? The bigger the resistance of a component, the the current through it. Use this equation to work out the current through a component in a parallel circuit. The current in a diode flows in one direction only, in the reverse direction the diode has a very high resistance so the current will be what? Thermistor: Resistance if its temperature increases. LDR: resistance decreases if the light intensity on it. diode filament bulb resistor thermistor

13 P2 REVISION PART 5 MAINS ELECTRICITY Alternating Current Direct current is supplied by cells and batteries and passes round the circuit in one direction. Alternating current is from the mains, how does it travel? Frequency of am ac supply can be worked out from an oscilliscope trace using the equation: Fuses How does a fuse work? Where is a fuse fitted in a circuit? How does a circuit breaker work? Electrical Energy & Charge An electric current is the flow of what? What is the equation that relates to charge, current and time? When charge flows through a resistor, what makes it hot? What can you use this equation for? Cables & Plugs Why are the pins of a plug made of brass? What does the earth wire earth? Why are some cables thicker than others? Electrical Power & Potential Difference Power can be calculated using the above equation. Using the current and the pd and the equation above enables us to calculate the power of an appliance. To work out the correct rating in amperes for a fuse rearrange the above equation, what would the equation now be? current frequency oscilloscope circuit breaker Electrical Issues Electrical faults are dangerous what two things can they cause? Why must you check cables, plugs and sockets for damage regularly? What must you not touch with wet hands? Why are filament bulbs very inefficient?

14 P2 REVISION PART 5 MAINS ELECTRICITY What is the difference between direct current and alternating current? What is a fuse and how does it work? Why do we use alternating current for mains electricity? What is a circuit breaker and how does it work? How do we measure alternating current? In a standard 3-pin plug what is...? Electrical energy and charge Work through these questions: Calculate the charge flow when the current is 8A for 80s. Q = I X t X: Y: Z: Z Calculate the energy transferred in a component when the charge passing through it is 30C and the potential difference is 20V Energy transferred = volts X coulombs How do the materials and design of the following plug parts improve their safety? case fuse pins How are electrical cables designed to be safe? direct current alternating current frequency live/neutral/ earth wire Oscilloscope Y-gate control time base control socket plugs cable three-pin plug circuit breaker residual current circuit breaker (RCCB)

15 P2 REVISION PART 6 RADIOACTIVITY Observing Nuclear Radiation Nuclear Reactions An atom has a small central, which contains the and, this is then surrounded by. α decay Change In The Nucleus Particle Emitted The nuclei of radioactive substances are unstable, to become stable they go through a process called radioactive decay. The 3 types of radiation emitted are: β decay Where does background radiation come from? Remember: Radioactive decay is random we cannot predict or influence when it happens! Discovery of the Nucleus Scientists originally called the model of the atom the plum pudding. Rutherford, Geiger and Marsden then did an alpha particle scattering experiment, they fired alpha particles at thin gold foil. Most passed straight through the foil, what does this mean? proton neutron electron Relative Mass Relative Charge What is an atom called if it loses or gains electrons? What is an isotope? When a nucleus emits an alpha particle the atomic number goes down by and the mass number goes down by. When a nucleus emits a beta particle the atomic number goes up by and the mass number stays the same. Is there any change when a nuclear emits gamma radiation? Some of the alpha particles are deflected through small angles, what does this mean? A few rebound through large angles what does this mean? ion isotope nucleus proton electron radiation

16 P2 REVISION PART 6 RADIOACTIVITY Half-Life What is the half-life of a radioactive isotope? Alpha, Beta & Gamma Radiation Remember what stops each type of radiation. The number of atoms of a radioactive isotope and the activity both decrease by every half life. Deflected by? How ionising? Alpha electric & magnetic fields Alpha Beta Radioactivity At Work Where Used And Length Of Half-life Tracers in medicine. Half-life of a few hours so that patient is not exposed to unnecessary radioactivity. Beta Gamma deflected by neither electric or magnetic fields. not as ionising as alpha particles Ionisation is when nuclear radiation travels through a material, colliding with the atoms within it. This then knocks electrons off, creating ions. Radioactive Dating: What is this used for? What do we need to do it? ionisation half-life tracer radioactive dating

17 P2 REVISION PART 6 RADIOACTIVITY What is radiation? Give 3 uses of radioactivity, and a brief description of how they work: How did each of these scientists contribute to our understanding of radiation? Henri Becquerel: What causes background radiation? Marie Curie: Ernest Rutherford: Properties of radiation: Penetrating Power Deflection By Magnetic Field Deflection By Electric Field Explain what half-life is: Fill in this table assuming there is a 10% decay every hour: Time from start (hours) No. of unstable atoms No, of unstable atoms that decay in the next hour radioactivity alpha beta gamma

18 P1 REVISION PART 7 ENERGY FROM THE NUCLEUS Nuclear Fission Nuclear fission is the splitting of a nucleus into two approximately equal fragments and the release of two or three neutrons. What two fissionable isotopes are most commonly used in nuclear reactors? The Early Universe How and when do many scientists think the universe was created? When does a chain reaction occur? What pulled the gas and dust together to form stars? What are very large groups of stars called? Nuclear Fusion Nuclear Issues Nuclear fusion is the process of forcing two nuclei close enough together so they form a single larger nucleus. What is a major source of background radiation? What is released when this happens? Name two other sources of background radiation. Where does nuclear fusion take place? How is nuclear waste stored? Why must it be stored securely? star nuclear fusion chain reaction nuclear fission

19 P1 REVISION PART 7 ENERGY FROM THE NUCLEUS Life History Of A Star How The Chemical Elements Formed Protostar: Gas and dust cloud in space that can go on to form a star. Low mass star: Protostar main sequence star red giant white dwarf Black dwarf High mass star: Protostar main sequence star red supergiant Supernova black hole if sufficient mass. Gas, rocks and dust The sun forms at the centre of a spinning cloud of dust, gas and rock. The sun s energy evaporates ice and drives gas away from the inner solar system, leaving rocks behind. What will the sun eventually become? What is a supernova? The rocky planets form near the Sun and the gas giant planets form further away. The minor planet Pluto orbits the Sun beyond the giant planets. Elements as heavy as iron are formed inside stars as a result of nuclear. Elements heavier than iron are formed in supernovas, along with lighter elements. What were the sun and the rest of the solar system formed from? pro star supernova neutron star

20 P1 REVISION PART 7 ENERGY FROM THE NUCLEUS Explain nuclear fission (use diagrams): What was the early universe like? Explain the life cycle of a star: Explain nuclear fusion (use diagrams): How are chemical elements formed? What are some of the issues linked with nuclear energy? nuclear fission chain reaction reactor control rods coolant nuclear fusion protostar neutron star main sequence stars red giant white dwarf black dwarf supergiant supernova black hole