Motion 3.1 Flashcards
Is displacement a scalar or vector quantity?
-Displacement is a vector quantity a because it has both size and direction
Is speed and velocity a vector or scalar quantity? and give equations for both?
-speed is a scalar quantity because it only has a magnitude
-Velocity is a vector quantity because it has both magnitude and direction
-Average speed=total distance travelled/time taken
-Average velocity=total displacement/time taken
How to find total displacement from a displacement time graph?
-How far away the graph finishes from the starting point.
What is acceleration?
-Acceleration is the rate of change of velocity:
-Acceleration=change in velocity/time taken
What are the constant acceleration equations?
On a displacement time graph what represents increasing acceleration and deceleration and a constant velocity
-Increasing acceleration and deceleration=curve upwards and curve downwards but still with positive gradient
-Constant velocity=Constant gradient
On a velocity time graph what indicates constant acceleration and deceleration and constant velocity?
-Constant acceleration= diagonal line with positive gradient
-Constant deceleration=Diagonal line with negative gradient
-Constant velocity= line along the x-axis
What is the value for acceleration due to gravity
9.81m/s^2
Why do objects with different masses fall at the same rate?
Why is it better to use motion sensors and light gates than a stopwatch when determining g
-Motion sensors and light gates are more accurate as they remove reaction time
What are the two methods for determining acceleration due to gravity and what conditions are needed?
-Direct approach: timing a ball falling and using equations of motion
-Indirect approaches: for e.g measuring the time taken for a pendulum to do a full swing
-The object needs to be close to the earths surface so it doesn’t reach terminal velocity
How can you do an experiment to get acceleration due to gravity using a trap door and an electromagnet?
- When the electromagnet is turned off the steel ball drops and hits the trap door, this is connected to a timer which times how long it takes for ball to drop
- Use S=ut+1/2at² to get a value for g and repeat for different distance to get a mean g
What is the equation for stopping distances and the definitions of the other distances it depends on?
-Stopping distance=thinking distance + braking distance
-Thinking distance: the distance the car travels between the driver seeing the hazard and applying brakes
-Braking distance: distance car travels between applying brakes and coming to rest
Factors that increase thinking distance?
-Higher speed
-Age of driver
-Distractions
-drugs and alcohol
-tiredness
What is the equation for thinking distance?
-Thinking distance= reaction time of driver * speed of car
Factors that increase braking distance?
-Higher speed
-Conditions of brakes and tires
-mass of car
-Poor road conditions (icy)
How does braking distance increase with speed?
