Chapter 1 - Analysing Motion Flashcards
If air resistance is ignored, what are the only forces acting on a projectile?
If air resistance is ignored, the only force acting on a projectile during its flight is it’s attraction to the Earth due to gravity.
Gravity - constant, directed vertically downwards causing the projectile to continually deviate from a straight line path to follow a parabolic path.
What is a Projectile?
It is any object that is thrown or projected into the air and is moving freely. (It has no power source)
Does the horizontal component change when gravity is acted upon a projectile?
No, a projectile movies with uniform velocity since there are no forces acting in this direction.
Why would a taller athlete have an advantage in the shot-put?
They launch the shot from a greater heigh and a will achieve a greater distance. Recent female world champions have been around 2.0m tall.
Is the sum of the gravitational potential energy and kinetic energy the same at all points?
Yes, because at the lowest point in its flight, gravitational potential energy is a minimum and kinetic energy is maximum. And vice versa for the highest point.
Why ballet dancers seem to float in the air?
They raise their arms and legs which allows them to raise the position of their centre of mass so that it is higher in the torso. The effect of this is that the dancer’s head follows a lower and flatter line.
What is a Period?
It is the time taken to move once around the circle.
Average Speed of an object moving in a circular path is:
v = 2 pie r / T
v = distance/ time period
Define Frequency (f).
The number of revolutions (or rotations) completed in one second. (Hz) or (rpm).
Define Speed (v).
This refers to the linear speed of a point moving in a circular path. Often just called the velocity.
Define Rotational Speed.
This, like frequency is simply the number of rotations/ revolutions per second. Sometimes also called angular speed. (Hz) or (rpm).
What is the Universal Gravitational Law?
Between any 2 physical objects there is an attraction force directly proportional with their masses. And indirectly/ inversely proportional with the square of the distance between their centers.
Is the velocity of an object kept constant when it is moving in a circular path?
No, it is changing.
How does the velocity of an object moving in a circular path constantly changing?
It is accelerating even thought its speed is not changing. (Direction)
What does Centripetal Acceleration mean?
‘Centre-seeking’. Acceleration towards the centre; however, even though the hammer is accelerating towards the centre of the circle, it never gets any closer to the centre.
Ac = v^2 / r
