P3 Flashcards
-What are the three units of measurement for speed?
m/s, km/h, mph
What is the definition of ‘speed’?
A measure of how fast an object is moving
What does ‘m/s’ stand for?
Metres per second
What does ‘km/h’ stand for?
Kilometres per hour
What two measurements are needed to work out the speed of a moving object?
The distance it travels, and the time taken to travel that distance
What does ‘mph’ stand for?
miles per hour
What diagram is used to calculate speed, distance and time?
When the speed changes over a given distance, what is the formula used to calculate the distance?
Distance = average speed x time
How do speed cameras work?
They take two pictures of a vehicle a certain amount of time apart. The vehicle’s position in relation to the distance markings on the road in the two pictures can be used to calculate its speed.
What is the equation to calculate the speed of a car using information from a speed camera?
speed of car= distance travelled between pictures/time taken between first and second picture
On a distance-time graph, what is the relationship between the gradient (slope) and the speed?
The steeper the gradient, the greater the speed.
How can you work out the speed of an object from a distance-time graph?
Take any two points on a distance-time graph and read off the distance travelled for that part of the journey, and the time taken to get there. The formula is
speed= end distance-start distance/time taken
What is the acceleration/deceleration of an object?
The change in speed per second
What is the only unit for acceleration?
m/s²
Which two measurements are needed to calculate the acceleration/deceleration of an object?
The change in speed, and the time taken for the change in speed.
What formula is used to calculate acceleration (or deceleration)?
Acceleration (m/s²)=
change in speed (m/s)/time taken for change (s)
What does the slope of a speed-time graph represent?
The acceleration of the object.
On a speed-time, what does an object moving at a constant speed show?
That it isn’t accelerating.
What does the value of the area underneath the line in a speed-time graph show?
The total distance travelled.
How do you work out the acceleration of an object using a speed-time graph?
Take any two points, and read off the change in speed over the chosen peripd, and the time taken for the change.
The formula is:
Acceleration= end speed-start speed/time taken
How can the total distance travelled be calculated using a speed-time graph?
By working out the area under the speed-time graph.
When lifting an object, what is the definition of the force applied?
The weight of the oject, measured in newtons
What is the unit of measurement for both energy and work done?
Joules
What is the equation for calculating work done?
work done (J) = Force Applied (N) x Distance moved in direction of force (m)
What are the two measurements needed to calculate word done?
Force applied, and distance moved in direction of force.
What is the definition of power?
A measure of how quickly work is done.
What is power measured in?
Watts (W)
Why is a car having high fuel consumption bad?
Expensive for the driver, and damaging to the environment.
What is the equation to work out power?
Power (W)= Work done (J)/Time (s)
or
Power (W)= Force (N) x Velocity (m/s)
How many metres is in 1km?
1000
How many metres is 1cm?
0.01
How many seconds are in an hour?
3600
What is kinetic energy?
The energy an object has because of its movement.
What two measurements are needed to work out the kinetic energy of an object?
Its mass and its speed
What is the relationship between a car’s kinetic energy and its braking distance?
The greater a car’s kinetic energy, the greater its braking distance
What is the equation to calculate kinetic energy?
Kinetic energy (J)= 1/2 x mass (kg) x speed² (m/s²)
Give three examples of frictional forces.
Friction, drag and air resistance
How does the shape of a badminton shuttlecock influence its top speed?
It increases air resistance so it travels slowly
How does the shape of a parachute influence its top speed?
They have a larger surface area, which increases air resistance
What can greater drag lead to on vehicles?
Energy loss, inefficiency and greater fuel consumption
How can frictional forces be reduced?
By changing the shape of the object, or using a lubricant
Why does a lubricant help reduce frictional forces on an object?
Because it makes the object slide through the air with less resistance
