P10 forces Flashcards
What is the breaking distance
The distance travelled A vehicle after the driver has. Applied the break
What is the only way to reduce mass
If you remove some matter
What is weight measured in and why
N because it is a force acting on an object due to gravity
What is fluid
A liquid or gas
What is terminal velocity
The maximum velocity an object can reach
When does terminal velocity occur
When the weight of an object is equal to its drag force
What is thinking distance
The distance travelled while the driver is reacting to the situation
What is the stoping distance
The breaking distance+ the thinking distance
What is the equation for momentum
P= M x V
What is extension
Stretched length - original length
What is hookes law
The extension of a spring is directly proportional to the force applied
What is spring constant equal to
It is equal to the force per unit extension the stiffer the spring the greater the spring constant
What is the limit of proportionality
It is wher hookes law no longer continues so when the extension is not directly proportional to the force applied
Describe a method used for hookes law
Set up a clamp stand with a ruler clamped in. Then attach a spring onto the clamp. Then attach the splint onto the spring to use as a fiducial marker on the metre ruler. Add a hanging mass to the spring and add 10p gram weight and record the extension of the spring by reading the length of the scratched spring
What is elastic
An object is elastic if it goes back to its original shape after being deformed
What is the elastic limit
The limit of the object so that it is permanently deformed and does not return to its original shape
What is inelastic deformation
When an object is deformed but does not go back to its original shape
How can a vehicle travel at a steady speed
When the driving force is balance to the frictional force
When does friction occur
When two surfaces in contact or when an object passes through a fluid
What is drag
Drag is the resistance you get in a fluid
What is air resistance
A type of drag
What happened to the speed of an object falling
When a falling object first sets off the force of gravity is greater than the frictional force so it accelerates force
When speed increases friction builds up which gradually reduces the acceleration until eventually the frictional force is equal to the accelerating force therefore it would’ve reached its terminal velocity and will fall a steady speed
What determines terminal velocity of an object
The shape an area of an object so if an object is less streamlined it will have a lower terminal velocity
Why would a beachball have a lower terminal velocity than a marble one falling
The beach ball. Has a larger surface area so it will experience more air resistance therefore the resultant force will reach zero sooner so it has a lower terminal velocity
When will the terminal velocity be zero of a falling object
When it’s resultant force is zero
What happened to the resistive force of an object that is accelerating
Increases
What is Newton’s first law
A resultant force is needed to make something to start moving to speed up or slow down so if the resultant force on a stationary object zero the object will be stationary but if the resultant force on a moving object zero it will remain at the same velocity
What is newton second law
Acceleration is directly proportional to G force applied so the larger the resultant force acting on an object the larger the acceleration of the object
What is the formula for resultant force
Acceleration time is mass
. What is inertia
The tendency to continue in the same state of motion
What does inertial mass measure
How difficult it is to change the velocity of an object
What is Newton’s third law
When two objects interact the forces they exert on each other are equal and opposite
What is acceleration inversely proportional to and what does newton second law says about the acceleration of a larger mass and a smaller mass
Acceleration is inversely proportional to the mass of an object object with a larger mass will accelerate less than one with a smaller mass
What is a typical speed of a vehicle
25 mph
Describe an experiment used to investigate the effect of forces on Newtons second law
Attach a trolly with a piece of cardboard to a string that goes over a pulley and connected on the other side to a hook then place a light in the system
Mark a starting line for the trolly
And and add 700 grams on to the hook
Then let go of the trolly and record the acceleration shown by the light gate
Then remove a weight and place it on top of the trolly to keep the total mass of the circuit the same but change the force repeat this with all the masses
And repeat the experiment as a whole and calculate a mean
How can you investigate the affect of mass Newton second law experiment
I added a massive trolley instead of the. So it only changes the mass and not the force
Hey student investigate the effect of masses on a trolly to acceleration
By adding masses to the trolly explain why this experiment will not correctly show the relationship between the mass and acceleration of the trolley
To test the effect of masses on acceleration the force must be constant and by adding weights to the trolley it will increase both mass and force so the effect of masses cannot be found
What happened in an emergency stop
This is when the maximum force is applied by the breaks in order to stop the car in the shortest possible distance
What factors affect breaking distance
Speed faster the vehicle travels the longer it takes to stop
The weather or road service
Condition of tires
The brake quality
What is the formula for acceleration initial speed final speed and displacement
V squared - u squared = 2as
Explain the importance of a car having brakes and tires that are in good condition
If the tires are in good condition it will increase the amount of grip between the roads and tires so it will decrease the breaking and stopping distance in wet conditions therefore the car will be less prone to skid and crash in rainy weathers
if the brakes are in good condition it will allow a larger braking force to be applied onto the wheels which means the breaking distance is shorter and the brakes are less likely to overheat under a large break in force and the car will not go out of control
What is the typical reaction time for a person
0.2 and 0.9
Describe methods that can be used to test reaction times
The ruler drop test and a computer-based test
What unit should displacement be in the acceleration equation
Metres
Suggest two ways the ruler drop test can be a fair test
Use the same ruler for every experiment and always had the same person dropping the ruler and the same person catching the ruler
Describe the steps involved when using the ruler drop experiment
Hold a ruler between the four finger and thumb of the subject then align the finger with the zero on the ruler without warning drop the ruler so that the subject will catch it between their fingers then read the distance fell by the ruler by reading the scale and then use V squared minus U squared equals 2AS to calculate the velocity and then use acceleration equals velocity divided by time to find the reaction time
Explain the safety implications of a man driving home late at night listening to loud music
It is dark at night so the driver may not see any hazards the loud music may be a distraction to the driver so he may not hear hazards and the distraction of the music will increase the reaction time and stopping distance of the car soon the driver may not be able to stop fast enough for an upcoming as a hazard and it may result in a car crash
What is the conservation of momentum
In a close system the total momentum before an event is the same as after the event
Newtons cradle consists of a cradle and five balls attached to it when the first ball is swung it hit the other balls and the last ball then swings and repeat the velocity of the first ball when it hits the second ball is equal to the final ball when it starts to move why is this
The total momentum of the balls are equal at the beginning the total momentum of the system is the mass of the five balls and the velocity of the first board that swings so as the first ball hits the line of balls it transfers momentum and comes to a stop this is then transferred along the line opposed to the last ball which has the same momentum as the first ball which is why the balls in between do not move
How can to students investigate reaction time to find if listening to music changes reaction times
Measure the distance the student catches the ruler by reading where their fore finger and thumb lies And the greater the distance the greater the reaction time then repeat the measurement and calculate a mean then. Repeat the experiment with the student listening to music and calculate a mean
A significant difference between the two means would show that music affect reaction time
Explain two possible reasons for anomalous results when doing the ruler drop test
The student was distracted the room was noisy
The total momentum of the gun and paintball just after the gun is fired is what to the total momentum of the garden and the paint will before the gun is fired
Equal to
Why is it important to pull the trolley at constant speed when investigating the friction between a sled and a surface
If the sled is accelerating the value for friction will not be constant so it will be wrong
Explain why if the sled is pulled at an angle to the surface constant friction will not be appropriate
Only the horizontal force will pull the sled forwards pulling it at a vertical angle would lift the sled therefore reducing the force of the object on the surface hence reducing the friction
Why would an objects acceleration decrease after a few seconds from leaving an aircraft
Because as the object is accelerating the frictional force will increase therefore it will reduce the resultant force and resource the force is directly proportional to the acceleration
A train can accelerate without changing speed how can this happen
Seller addition is the rate of change in velocity so as the train changes direction the velocity will change however the speed will not
A crate is travelling at a constant speed why will the frictional force be equal to the driving force
Because the resultant force is zero
Explain how a student will set up an experiment to find the centre of mass of an a iregular shape
Set up a clamp and punch several holes around the edge of your a iregular shape
That suspend the card onto the clamp and use a plum line since suspended from the same point as the card
Then using the plumbline as a guide draw straight lines across the card
Then suspend the shape on using a different hole and draw another line
Where are the lines cross is where the centre of mass is
Explain how a student can check the position of the centre of mass is accurate when doing the test for the centre of mass of an a irregular shape
Make more holes with the same card and use the plumbline to draw more lines if all of the lines cross at he same point it is accurate
A fisherman pulls a boat boat towards land deficient and exerts a force of 300 N to the right and the sea exerts a resistive force of 250 N what is the motion of the boat
The boat is accelerating and is moving to the right with a force of 50 N
A fisherman pause the boat towards land and the resistive force of the sea is 300 N and the force the fisherman is exerting is also 300 N why will the boot to be moving at a constant velocity to the right
Newton‘s first law states that when the forces of an object are in equilibrium the object will remain constant therefore the boat will continue in the same direction at the same speed
A new bus must have a stability test suggest why the bus will topple over if a ramp is tilted to great of an angle during the stability test
Because the line of action at the weight Will be outside of the bus
When doing the best ability test the bus is tested to angles of tilt far greater than it would’ve experience in normal you suggest why
Passengers on the bus may affect the position of the centre of mass of the bus
In normal use the centre of mass may be in a different position
