Forces In Motion Flashcards
Define distance?
Total length between two points
Define speed?
Total distance travelled per unit of time
Define displacement?
Distance of an object from a fixed point in a specified direction
Define velocity?
The rate of change of displacement of an object
What is acceleration?
The rate of change of velocity of an object
How do we find instantaneous speed on a graph?
Draw a tangent to the curve
Features of a displacement time graph?
Gradient = velocity
Y intercept = initial displacement
Diagonal straight line represent constant velocity
Curved line represents acceleration
Horizontal line represents rest
Features of a velocity time graph
Gradient = acceleration
Y intercept = initial velocity
Straight line represents uniform acceleration
Positive slope = increase in velocity (positive direction)
Negative slope = increase in velocity (negative direction)
Curved line represents non-uniform acceleration
Horizontal line = constant velocity
Area under the graph = displacement
Features of an acceleration time graph?
Gradient is meaningless
Y intercept = initial acceleration
Horizontal line represents constant acceleration
Area under the graph = change in velocity
Describe the motion of a bouncing ball
Acceleration due to gravity is always in the same direction
Positive velocity when travelling in the positive direction
Negative velocity when travelling in the negative direction
Positive direction is upwards
Negative is downwards
Highest point velocity is zero
At the highest point acceleration is negative whilst at lowest point it’s positive
Suvat key terms
Start from rest :
- u= 0
- t= 0
Falling due to gravity means acceleration is 9.81
Doesn’t matter which way is positive or negative as long as the values are consistent
- if downwards is negative, s must be positive and a must be negative.
How are trolleys used to study collisions?
They are composed of:
A light block of wood or plastic
Ball bearing wheels (to reduce friction)
A spring loaded plunger (for collisions)
A flat top surface to allow stacking or additional masses to be added.
How can we study collisions using air track gliders?
Used to investigate conservation of momentum
Reduce friction so energy lost to overcoming friction is minimised and the collision is as elastic as possible
How are ticket times good for analysing motion?
A long tape attached to a moving trolley and threaded through a device that placed a tick upon the tape at regular intervals of time
The ticket timer will produce a certain number of dots per second on the tape which will travel the same speed as the trolley
Distance between the dots and the time can be used to determine the velocity
Distance between the dots increases shows that the acceleration of the trolley is constant
How can we use light gates?
Measure time taken for a trolley to move a set distance
Card is attached to the top of the trolley as this will interrupt the beams on the light gate
The trolley is released from the top of the ramp with one light gate just in front of the release point and the other at the bottom of the ramp
Time taken to travel between light gates t can be used to workout the initial speed u and final speed v