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51 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Define scalar quantities |
Scalar quantities have a size/magnitude but no specific direction. |
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Give 5 examples of scalar quantities |
●mass ●speed ●distance ●energy ●temperature |
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Define vector quantities |
Vector quantities have a size or magnitude, and a specific direction |
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Give 5 examples of vector quantities |
●force or weight ●velocity ●displacement ●acceleration ●momentum |
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Offer the calculation for SPEED |
Speed (m/s) = change in distance (m) ÷ time taken |
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Offer the calculation for average speed |
Average speed (m/s) = total distance travelled (m) ÷time taken (s) |
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On a distance time graph what is shown by the following? A) a straight line with a moderate positive gradient(sloping) B) a horizontal line C) steep line, positive strong gradient |
A) shallow gradient shows the object is moving slowly yet accelerating B) The object is stationary either stopped or travelling at constant speed C) steep line student is accelerating and moving fast (er) |
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Define Offer the calculation for acceleration |
●acceleration is the change un velocity per secound, its a vector quantity. ● acceleration (m/s2)=change in velocity (m/s) ÷ time taken (s) |
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Define velocity and offer its calculation |
●velocity is the change in distance per secound (Final velocity)2 - (initial velocity)2 = 2 x acceleration x distance |
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Offer some facts to interpret a velocity/time graph |
●velocity is plotted on the y-axis and time is plotted on the y axis ● the graph shows you how velocity changes over time ●gradient shows us the acceleration of the vehicle ●the area under the graph tells us the distance travelled |
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How can speed be determined in the laboratory ? |
By using light gates & other equiptment. You can measure speed of objects in a lab by using light gates connected to a computer/data logger. ●vehicle is released from starting position and moves down the slope ●the speed is found fromthe legnth of card ÷ time ●when the card leaves the light gate, the light beam stops the timer ●the light gate is attached to laptop ●the light beam is cut by the card as it enters the light gate and thw timer starts●the beam remains until the back of the card passes through the light gate starts ●the beam remains until the back of the card passes through the light gate |
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How can the speed of falling objects be measured? |
●using light gates ●the acceleration due to gravity on earth is close to 10m/s2. This means that a falling object will increase its speed by 10m/s per secound when falling in the absence of frictional or restrictive forces. Howver, for a piece of falling paper, this terminal value wil decrease considerably because of resistive forces |
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What is stated bt newton's first law? |
A body will remain at rest, or continue at a straight line at a constant speed as long aa the forces acting on it are ballanced. |
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Describe the forces acting on a stationary object |
The forces acting on a stationary object are balanced Eg a ball with 25kg of tension and 25kg weight in effect in opposite directions |
Newtons first law |
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Describe the forces acting on a car thst is travelling at constant speed |
● the forces acting on a body moving in a straight line at a constant speed are ballanced ●it's a common mistake to believe if the resulatant force on an object is 0, the object is stationary, the object may also be travelling at a constant speed |
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A force of friction acts on a car 5n to the left, and accelartion in parralel works at 10n to the right, where will the car travel? |
The car will accelerate to the right, as there is a resulatant force of 5N to the right |
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What does newtons secound law state? |
When a resulatant force acts on an object there will be a change in its velocity. The resultant force determines the size and direction of the subsequent direction of the mass. |
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What is a resultant force? |
●when two or more forces act in the same like or are parallel, they can be added together to find the resultant force ●two or more forcez acting on an object can be replaced by one force, the resultant force ●forces have direction (vectors) so a force of -1N is in the opppsite direction to be a force of 1N |
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Give the calculation for force, mass and acceleration |
Acceleration (m/s)2 = force (N) ÷Mass (kg) |
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Give facts in assosiation with force, mass and acceleration |
●the acceleration is in the same direction as the force ●when the resultant force is 0, the acceleration is 0 ● a negative force means that the object is accelerating backwards or slowing down ●inertial mass is a mesure of how difficult it is to change the velocity of a moving object and is defined by the ratio force over acceration. |
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Define and compare both weight and mass |
Weight is the force that a body experiences due to its mass and the size of the gravitational field its in Weight is a vector quantity and is measured in newtons The weight of body on the surface of the earth acts inwards towards the earth's centre Mass is a measue of the amout of matter contained within a 3D space, its a scalar quantity measued in kilograms The mass of a body is not impacted by the size of he gravitational field its in |
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What equation would you use to find the weight of an object? |
●weight (N) = mass (kg) x gravitational field stregnth (N/kg) |
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What does gravitational field stregnth depend on? |
●the mass of the body The radius of the body When a body has a large mass and small radius , it will have a large gravitational field stregnth. Gravitational field stregnth is measured inN/Kg ●different astromical bodies will have different gravitational field stregnth |
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A scientist wants to determine the relationship between force, mass, and acceleration. Describe an invstigation in which he could do so |
If you are aiming to investgate mass effect on the acceleration of a trolley, you will need the following aparatus: Trolley, light gates, data logger, card of known legnth, slope or ramp, masses. 1. Choose a desired gradient for your ramp, proping it up securely, a wooden block can be useful, a flat surface suchh as a table is an additional aid. Place the light gates that should be clamped over the ramp, an adequate distance between them. 2. Set up the light gates to take velocity and time readings for you 3. Record velocity and time for different values of mass on the trolley. 4. Word out acceleration by dividing the difference in the velocity values by the time taken for the card to pass between both gates 5. If you are changing the mass, the gradient must stay the same throughout the investigation. In conclusion, the results should show the mass of the trolley does not depend on the mass of the trolley. The acceleration will remain failry constant throughout. |
Ramp and trolley |
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A body with still move in a circular path if its __________ is at right angles to a ______ that acts inwards along the _______ of the path |
Motion Force Radius |
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A body moving in a circular path with constant speed still has a ___________. Speed is a ___________quantity. Velocity is a _________ quantity. The velocity of a body changes when either its _______ or _________ of__________ changes |
Changing velocity Scalar Vector Speed Direction Motion |
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Explain why circular motion happens |
For circular motion to occur there must be a force acting inwards along the radius of the circle. This is called the centripetal force. The object moves at right angles to this force. An example is a satelites obit around the earth: if there were no forces acting on the satelite, it would travel in a straight line. The gravitational force acting towards the earth acts on the moving satelite. This is the centripetal force and it acts at 90 degrees to the satelites direction of motion the speed of the satelite remains constant, but the velocity constantly changes due to the change in direction.This means the satelite is accelerating although its travelling at a constant speed. |
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Momentum and force of a moving body are closely related, and can be understood by the use of ___________ |
Newtons secound law of motion |
includes a name |
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The ___________ of an object depends on its mass and velocity |
momentum |
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what is momentum? |
Momentum is mass multiplied by velocity, so the units for momentum are a combination of the units for mass & velocity. |
multiplied |
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what is force? |
The rate of changing momentum. |
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how do you calculate the momentum of an object? |
momentum (Kg m/s) = mass (kg) X velocity (m/s) |
equation with units |
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How would you work out force? |
Force (N) = change in momentum (kg m/s) divided by time taken for change |
equation with units |
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When the mass or the deceleration of a vehicle are large, the forces exerted on the passengers are also large. This can be very dangerous. How do cars reduce this danger? |
car safety features help reduce this risk. For example seat belts and crumple zones reduce the size of forces acting on driver and passengers, by increasing the time over which a vehicle comes to risk. |
include the word time |
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how can you change the size of a force? |
by increasing the time over which the change in momentum takes place, the force is reduced. |
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what does newtons third law state? |
Newtons third law reelates to bodies in equilibrium and can be applied to collisions when considering the conservation of momentum. Newtons third law states for every action there is an equal opposite reaction. The action and reaction forces act on different bodies |
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just because two forces are equal and opposite doesn't always mean they are examples of newtons third law. Why? |
if both forces are acting on the same object, although they are in equal and oppisite directions, the force must act on different objects. eg if a man applied 100N of force to a wall (action) the WALL would exert 100N back (reaction) the wall and man are two different objects, therefore the wall and man are an example of newtons third law. |
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A police officer says "Car collisions obey with Newtons third law" do you agree with this statement? |
Yes, for example, if a car and truck collided, they would exert equal and opposite forces on eachother and are in contact for the same amount of time. Newtons third law is obeyed. Momemtum is conserved, the total momentum before the collision equals the total momentum after the collision. |
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what is human reaction time? |
human reaction time is the time between a stimulus occuring and a response It's related to how quickly the brain can process information and react to it. |
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typically, how long does it take a human to react to a figure
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between 0.20s and 0.25s |
its a 'between' decimal figure |
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What kind of people have a faster reaction time than average? |
People may be constantly testing their reaction times, eg international cricketers and sprinters, fighter piolets, and sprinters have trained themselves to have faster reaction times |
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Drivers must react to changes in traffic while driving, eg reacting to lights changing colour or avoiding a wild animal. What can this reaction time be affected by ? |
1) tiredness 2) alcohol and drugs 3) distractions 4)age |
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How could a student measure reaction time? |
using the ruler drop test. A meter ruler is held, by a partner so its vertical and exactly level with the persons finger and thumb, with the start of the ruler (lowest number) at the bottom. The ruler is dropped than grasped by the other persn If the ruler droped by eg a gap of 8cm you could use this equation to calc the reaction time: square root of 2x distance ruler falls divided by gravitational field stregnth Repeats should be used to get more reliable results and a mean value should be calculated for reaction time |
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stopping distance is the toal distance over which a vehicle comes to rest. knowing factors affecting stopping distance are important for road safety, what are they? |
danger appears... THINKING DISTANCE distance the car travels while driver reacts to danger and applies breaks between the driver applying breaks and the car stopping is the BRAKING DISTANCE, the distance a car travels while its slowing down. |
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Thinking and stoping distance increase when a cars speed increases. When you double the speed of a car, the thinking distance _______, but the braking distance increases by factor of _______ |
double four |
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when does thinking distance (drivers reaction time) increase ? |
when the driver is tired, distracted, or has taken alcohol or drugs |
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when does a cars breaking distance increase? |
when the amout of friction between the road and tyre decreases. when the road is icy or wet when the breaks or the tyres are worn when the mass of the car is larger |
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thinking distance is _____ proportional to _______, |
directly speed |
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Energy can be stored in different ways, and can be transferred from one energy store to another. there are 8 main energy stores, state them and give an example of each |
1. CHEMICAL eg feul, food, battery 2. KINETIC eg moving objects 3. GRAVITATIONAL POTENTIAL eg raised mass 4. ELASTIC eg stretched spring 5. THERMAL eg hot object 6. MAGNETIC eg two magnets 7. ELECTROSTATIC eg two charges 8. NUCLEAR eg radioactive decay |
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In ______ systems when there are ______ ____, there is ___ chanfge to the _______ _____ in the system. A closed system is where energy can flow ____ or _____ of the system, but there is ___ transfer of ______. An example is a pan of water being heated with a _____ on it so no steam can _____ |
closed energy transfers no total energy in out mass lid escape |
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What are the 4 ways in which energy can be transferred from one system to another? |
mechanically (by a force moving through a distance) |
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