Sp2- motion and forces Flashcards
What does a straight uphill section show on a dist time graph?
It is travelling at a steady speed
What does it mean if the line is getting steeper on a dist time graph?
The faster it is going
What do flat sections mean on a dist time graph?
This is when the object is stationary
What does a steepening curve show on a dist time graph?
That it is accelerating
What does a levelling off curve show on a dist time graph?
It is decelerating
How do you work out the speed on a dist time graph?
The gradient of the line
How do you find the speed of a curved line on a dist time graph?
You draw a tangent to the curve and work out the gradient of the line
What does a flat line show on a velocity time graph?
It is travelling at a steady speed
What does a steep line on a velocity time graph show?
The steeper the line, the greater the acceleration
What do downhill sections on a velocity time graph?
That it is decelerating
What does a curved line show on a velocity time graph?
That it is changing acceleration
How do you work out the acceleration of a velocity time graph?
You work out the final velocity - the initial velocity and divide it by the time it takes
How do you work out the dist travelled of a velocity time graph?
Work out the area underneath the graph
What is a resultant force?
If you have a number of forces acting on a single point and you can replace them by a single force which has the same effect as the original forces acting together
What is Newton’s first law?
That a resultant force is needed to change the motion of an object and a force is needed to change the speed of direction of the object
What will happen if a stationary object has a zero resultant force?
It will remain stationary
What happens if you have a zero resultant force on a moving object?
It will just carry on at a steady velocity
What happens if there is a non zero resultant force on an object?
It’s velocity will change so the object will either change speed or direction as velocity is a vector
What is Newton’s Second Law?
The larger the force, the larger the acceleration as they are directly proportional to each other
Acceleration is inversely proportional to mass so if you have an object with a larger mass it will accelerate less than an object with a smaller mass
Why do centripetal forces occur?
As when an object is travelling in a circle it is constantly changing direction and speed so it is changing velocity and therefore accelerating. There must be a resultant force being constantly applied to the object
What is an objects inertial mass?
How difficult it is to change the velocity of an object.
A bigger force needs to be applied to an object with a larger mass in order to change its velocity
Core Practical:
How does the weight of the trolley affect the experiment?
The weight of the trolley down the slope compensated for the friction acting between the wheels of the trolley and the ramp.
Core Practical:
How do you work out the velocity of the experiment?
You measure the length of the card and divide it by the duration of the interruption
Core Practical:
How do you work out the acceleration of the experiment?
You work out the velocity of the final gate and minus it from the velocity of the first gate and divide it by the time
Core Practical:
How can you reduce friction of the experiment?
You use an air slope to reduce friction
Core Practical:
How do you vary the mass of the experiment?
You add masses to the trolley one at a time to increase the mass of the system
Core Practical:
How do you vary the force of the experiment?
You keep the total mass of the system the same and change the weight of the hook
Core Practical:
Why is a light gate used rather than a stopwatch?
As measurements aren’t affected by reaction times
Core Practical:
How can you use a video camera to determine an objects speed?
You could work out the number of frames per second and you can find out the dist travelled by an object by knowing the time of the object
What is Newton’s Third Law?
When two objects interact, they exert equal but opposite forces of the same type on each other
How is equilibrium different to Newton’s Third Law?
As with equilibrium the objects are experiencing a zero resultant force and these forces could be different whereas with newton’s third law they are same type of forces
How does Newton’s third law affect momentum?
Newton’s third law causes opposite but equal forces to act which causes a change in momentum and these equal but opposite forces lead to the conservation of momentum in a collision
