Uniform Circular Motion Flashcards
When is a particle’s motion called uniform circular motion?
When the particle moves with a constant speed in a circular path
What happens to the speed and direction in uniform circular motion?
The speed of the particle is uniform, because a particle in circular motion travels equal distances along the circular path in equal intervals of time. But the direction of motion of the particle changes at each point of the circular path.
Why is the velocity of a particle in uniform circular motion variable?
This is because the speed of such a particle is uniform but the direction of motion of the particle goes through continuous changes at each point of the circular path. This implies that the velocity is non-uniform i.e., the motion is accelerated.
How to find the direction of motion of a particle in uniform circular motion?
At any point, the direction of motion is along the tangent drawn at that point of the circular path.
What is the difference between uniform circular motion and uniform linear motion?
In uniform linear motion, the speed and velocity, both are constant and therefore, acceleration is zero ; therefore, ULM is an unaccelerated motion, whereas in a uniform circular motion the velocity is variable (although the speed is uniform), so it is an acceleration motion.
Under the influence of which force is the motion in circular path possible?
Centripetal force
Give the meaning of centripetal
centre seeking
Where is the centripetal force directed at each point of the circular path?
Towards the centre of the circle
Define centripetal force
It is the force acting on a body moving in a circular path, in a direction towards the centre of the circular path
From where is the required centripetal force obtained in an atom?
In an atom, an electron moves around the nucleus in a circular path for which the required centripetal force is obtained from the electrostatic force of attraction on the negatively charged electron by the positively charged nucleus
From where is the required centripetal force obtained in a planet moving around the sun?
From the gravitational force of attraction on the planet by the Sun
From where is the required centripetal force obtained in the Moon moving around the Earth?
The gravitational force of attraction on the Moon by Earth provides the required centripetal force
From where is the required centripetal force obtained in a stone being whirled in a circular path?
The tension in the string provides the centripetal force
In the absence of which force will a stone not turn to move in a circular path?
In the absence of tension
Name a few instances where centripetal force is at play
- In an atom, an electron moving around the nucleus
- A plant moving around the sun
- The Moon moving around the Earth
- A stone being whirled around in a circular path
When a body moves under the influence of centripetal force, which state of equilibrium is it in?
Dynamic equilibrium
Under the influence of centripetal motion, a body has _ speed but _ acceleration as the _ keeps changing
uniform, variable, direction of motion
Define centrifugal force
A force assumed (by an observer moving with the body) to be acting on the body in a direction away from the centre of circular oath
Name the force which is not real, but fictitious
Centrifugal force
Which factor is equal in centrifugal and centripetal force and which, different?
Their magnitude is the same, the direction opposite
Why is the centrifugal force not the force of reaction of the centripetal force?
Because action and reaction do not act on the same body
Why does a person standing outside a merry-go-round observe that the ball is moving in a circular path?
For the person standing on the ground, the ball moves in a circular path because the tension T in the string provides the centripetal force needed for the circular motion
Why does the person standing on the platform of the merry-go-round observe the ball is stationary in front of him?
He considers the following 2 forces acting on the ball:-
- the tension T of the string towards the centre of the
merry-go-round - the centrifugal force away from the centre
The two forces are equal and opposite, therefore net force on ball is zero and it remains stationary
The person standing on the platform of the MGR can only explain the stationary ball when he considers?
The centrifugal force along with the force of tension in the string
If the string breaks of the rotating ball, what does the person at the platform of the MGR observe?
He will observe that the ball always remains in front of him moving radially away from him
To what does the person at the platform attribute the motion of the ball moving radially away from him?
To the centrifugal force acting on the ball away from the centre
If the string breaks of the rotating ball, what does the person on the ground observe?
That the ball is moving in a straight line along the tangent drawn at the position P of the ball on the circular path
Describe fictitious force
A force that really does not exist, but is considered to describe (or understand) a certain motion
Give another name for fictitious force
Virtual force
Which force is real in the situation of the ball being tied at the end of a string tied to a MGR?
The force of tension in the string acting towards the centre (i.e., the centripetal force)
