Flashcards in Topic 1 Deck (81)
What are vectors?
Quantities with a magnitude and direction
Is force a vector or scalar quantity?
Is velocity a vector or scalar quantity?
Is displacement a vector or scalar quantity?
Is weight a vector or scalar quantity?
Is acceleration a vector or scalar quantity?
Is momentum a vector or scalar quantity?
What is a scalar quantity?
A physical quantity that only has magnitude and no direction
What is magnitude?
Is speed a vector or scalar quantity?
Is distance a vector or scalar quantity?
Is mass a vector or scalar quantity?
Is energy a vector or scalar quantity?
Is temperature a vector or scalar quantity?
Is time a vector or scalar quantity?
What is distance?
How far an object has moved
What is displacement?
The distance and direction in a straight line from an object’s starting point
What does speed measure?
How fast you’re going with no regard to the direction
What does velocity measure?
How fast you’re going in a given direction (speed in a given direction)
What is the typical waking speed?
1.4 m/s (5km/h)
What is the typical running speed?
What is the typical cycling speed?
5.5 m/s (20km/h)
What is the typical speed of cars in a built up area?
What is the typical speed of cars on a motorway?
31m/s (112 km/h)
What is the typical speed of trains?
Up to 55m/s (200km/h)
What is the typical wind speed?
What is the typical speed of sound in air
What is acceleration?
The change in velocity in a certain amount of time
What is deceleration?
If something slows down, what happens to the change in velocity?
The change in velocity is negative
How would you estimate the acceleration or deceleration of an object?
1) estimate how long it would take for the object to stop moving - use the approximate symbol in front of the value (~)
2) put the estimate into the equation
What is constant acceleration known as?
What is uniform acceleration?
What is acceleration due to gravity?
Roughly equal to 10m/s² near the earth’s surface and had the same value as gravitational field strength, it is uniform for objects in free fall
What does the gradient give you on a distance/time graph?
The speed of the object
What do the flat sections on a distance-time graph mean?
The object has stopped
What does a steep graph mean on a distance-time graph?
The object is going faster
What do curves mean on a distance-time graph?
What does a curve getting steeper (increasing gradient) mean on a distance-time graph?
The object is speeding up
What does a levelling off curve (decreasing gradient) mean on a distance-time graph?
The object is slowing down
How can you find the speed of an object on a distance-time graph?
•if the graph is a straight line graph then the speed at any point along the line is equal to the gradient
•if the graph is curved then to find the speed at a certain time a tangent needs to be drawn to the curve at that point. then find the gradient of the tangent
How do you calculate the average speed of an object when it has non-uniform motion?
By dividing the total distance travelled by the time it takes to travel that distance
What is an example of non-uniform motion?
What is a tangent?
A line that is parallel to the curve at that point
What does the gradient of a velocity-time graph show?
The acceleration because acceleration = change in velocity ÷ time
What do the flat sections on a velocity-time graph show?
A steady speed
What does the steepness of a velocity-time graph mean?
Acceleration or deceleration, the steeper the graph the greater the acceleration or deceleration
What does an uphill section on a velocity-time graph mean?
What does a downhill section on a velocity-time graph mean?
What does a curve on a velocity-time graph mean?
How do you find the acceleration on a velocity-time graph if the graph is a curve?
draw a tangent to the curve at a point in order to find the acceleration at that point?
how do you find the distance travelled on a velocity-time graph?
find the total area under any section of the graph (pr all of the graph), this is equal to the distance travelled in that time interval because distance = speed/time
what is needed to change motion?
what is Newton's 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 (same speed and direction.)
as a result of Newton's first law, what is needed to make an object start moving, speed up, or slow down?
a resultant force
what will a non-zero resultant force always present in the direction of the force?
acceleration or deceleration, this can be taken in the form of stopping, speeding up, slowing down, and changing direction. acceleration is directly proportional to the resultant force
what is the relationship between acceleration and mass?
acceleration is inversely proportional to mass
what formula describes Newton's second law?
F = m x a
why can large decelerations of objects and people cause injuries (e.g. in car crashes)? How can this be combatted?
the large deceleration requires a large force, the force can be lowered by slowing the object down over a longer time (decreasing the deceleration)
what safety features do vehicles have to prevent injury due to large deceleration?
• seat belts
what are safety features in cars designed to do in order to prevent injury in car crashes etc?
to increase collision time which then reduces the force and so reduces the risk of injury
how do seat belts prevent injury in a car?
the seat belts stretch to increase the collision time
how do air bags prevent injury in a car?
the air bags slow the body down and so increase the collision time
how do crumple zones prevent injury in a car?
they crumple easily in the collision, increasing the time taken to stop
what are crumple zones?
areas at the front and back of a vehicle which crumple easily in a collision
how do brakes prevent injury in a car?
the brakes do work on the wheels of the car, transferring energy from the vehicle's KE store to the thermal energy store of the brakes. the brakes increase collision time
how may very large decelerations in a car affect the brakes?
the brakes could overheat (so the brakes are less effective), and the vehicle could skid
what would be an estimate for the mass of a car?
~ 1000 kg (~ symbol = approxiomate value)
what is weight?
the force acting on an object due to gravity (the gravitational force on the object)
how is weight measured?
using a calibrated spring balance or a newton meter
what is a centre of mass?
a point at which you assume the whole mass of an object is concentrated
where does weight act from on an object?
the centre of mass
what is the equation linking weight, mass and gravitational field strength?
W = m x g
why can gravitational field strength vary?
gravitational field strength varies with location, the gravitationalfield strength is stronger the closer you are to the mass causing the field (more massive objects form stronger fields.)
why does the weight of an object vary with location?
because gravitational field strenth varies with location
what does the gravitational field strength on earth equal?
describe what is happening to the forces of an object which is travelling in a circle at a constant speed.
• the objectis constantly changing direction so it is constantly changing veocity, therefore the object is accelerating
• due to the object accelerating, there must be a resultant force on the object
•the force acts towards the centre of the circle, it is a centripetal force
what is a centripetal force?
a force which keeps an object moving in a circle.
what is the gravitational field strength on the moon?
what masses does gravity attract?
all masses but it is only noticed when one of the masses is very large (like a planet)