PHYSICS1 Flashcards
Give four examples of elastic materials?
Rubber bands, rubber gloves, erasers and slinkies.
What is the definition of an elastic material?
Will return to the original shape and length if the force is taken away from them.
If we squeeze an elastic material (two forces) what will happen?
It will compress. (ELASTIC DEFORMATION.)
What happens if we apply three forces to an elastic material?
It will bend (ELASTIC DEFORMATION).
What does it mean if there is one force to a stationary object?
The forces are no longer balanced so it would not bend, it would just move.
What happens when we stretch an inelastic material?
It will not return back to it’s original shape.
Give one example of an inelastic material?
Certain polymers.
What is the equation for force?
Spring constant (n/m) X extension (m) WE CAN ALSO USE THIS TO CALCULATE COMPRESSION JUST REPLACE EXTENSION WITH COMPRESSION.
Work done=
Elastic potential energy- only if it is not inelastically deformed.
What is the limit of proportionality?
The object does not return to its original length when the force is removed. Hooke’s law no longer applicable.
What is the acceleration equation of the object is at a constant rate?
Velocity squared (m/s) -initial velocity squared (m/s)= 2 X acceleration (m/s squared) x distance (m)/
What is the gravitational field strength of the earth?
9.8 m/s squared.
What is meant by newtons second law?
The acceleration of an object is proportional to the resultant force acting on the object and is inversely proportional to the mass of an object. THE GREATER FORCE= GREATER ACCELLERATION.
What is the equation for force?
Force (n)= mass (kg) x acceleration (m/s squared)
What is the average speed of a car on the motorway?
30m/s
What is the average speed of a car on the main road?
13m/s
What is the average speed increase needed to go from a main road to a motorway?
2m/s squared (2000N)
What is meant by intertia?
Objects will stay still or keep the same motion unless you apply a resultant force.
What is meant by the inertial mass?
A measure of how difficult it is to change the velocity of an object.
What is meant by the stopping distance?
The total distance travelled from when the driver first spots the obstruction to when it stops. THIS INCLUDED THINKING AND BREAKING DISTANCE.
What is meant by the thinking distance?
The distance travelled by the car during the drivers reaction time.
What is included within the thinking distance?
Spotting the obstruction, making a decision and putting foot to the break.
What is meant by the breaking distance?
The distance the car travels from when the driver applies the breaks to when the car stops.
GREATER SPEED=
GREATER STOPPING DISTANCE.
How to we generally test reaction time?
The ruler drop test.
What can affect reaction time?
Being tired, substance intake, alcohol, distraction such as a mobile phone.
What can affect breaking distance?
Ice (as it reduces friction), and worn tires for the same reason.
Explain in detail how to carry out the acceleration and mass practical. (12 POINTS)
- Attach a piece of string to a toy car
- Make sure the string is looped around the pulley.
- At the other end of the string there should be a 100g mass.
- The weight of the mass will provide the force acting on the car.
- Get a timer.
- On desk draw chalk lines at equal intervals such as 10cm.
- Hold car at starting point and let go.
- because a resultant force is acting through string car will accelerate.
- Record the time the car passes through each interval.
- Record experiment on phone to get accurate timings.
- Repeat the experiment with a decreasing mass (80,60,40,20).
- Any mass we take from the car must be put on the car because overall mass of the object needs to stay the same.
What can cause a driver to loose control of their vehicle? (6 POINTS)
- Kinetic energy depends on velocity squared so if we double the velocity, kinetic energy quadruples.
- When a car is breaking, the break presses against the wheel.
- There is friction between the break and the wheel.
- Kinetic energy is converted to thermal in the brakes, so the temperature of the breaks increase and the car slows down because it looses kinetic energy.
- THE GREATER SPEED–> THE GREATER BREAKING FORCE. (you are decelerating rapidly).
- This can cause the breaks to overheat which can leave the driver to loose control.
