Qualification > Sciences
ALL CIE PHYSICS DOUBTS HERE !!!
astarmathsandphysics:
The compass points in the direction of the magnetic field, which is from south to north
ashwinkandel:
Questions from Circular Motion:
Q1.
Explain why the toy falls off when the speed of the turntable is increased.
Q2.
A teacher swings a bucket of water, of total mass 5.4 kg, round in a vertical circle of diameter 1.8m. [3]
i.Calculate the minimum speed which the bucket must be swung at so that the water remains in the bucket at the top of the circle. [2]
ii. Assuming that the speed remains constant, what will be the force on the teacher's hand when the bucket is at the bottom of the circle? [1]
Q3.
In a training, military pilots are given various tests. One test puts them in a seat on the end of a large arm which is then spun round at high speed, as shown in the diagram.
i. Describe what the pilot will feel and relate this to the centripetal force.[3]
ii. at top speed the pilot will experience a centripetal force equivalent to six times his own weight (6 mg)
a. Calculate the speed of pilot in this test. [3]
b. Calculate the number of revolutions of the pilot per minute. [2]
iii. Suggest why it is necessary for pilots to be able to be able to withstand forces of this types [2]
Q4.
The diagram shows a centrifuge used to separate solid particles suspended in a liquid of lower density.
a.The container is spun at a rate of 540 revolutions per minute
i.Calculate the angular velocity of the container. [2]
ii. Calculate the centripetal force on the particle of mass 20mg at the end of the test tube. [2]
b. An alternative methods of separating the particles from the liquid is to allow them to settle to the bottom of a stationary container under gravity. By comparing the forces involved, explain why the centrifuge is more effective method of separating the mixture. [2]
The diagram for questions 1 , 3 and 4 are attached below.
astarmathsandphysics:
1. The centripetal force is friction which cannot increases above a certain point (=mu R=mu mg where mu=coefficient of friction)
The centrifugal force is F=mv^2/r
When mv^2/r >mu mg the toy starts to slip
astarmathsandphysics:
2,3,4 in attachmwnts
Naruto123:
a) Calculate the displacement expressed as a fraction of the amplitude of a particle moving in simple harmonic motion with a speed equal to half of the maximum value .
b) Calculate the displacement at which the energy of the particle has equal amounts of kinetic and potential energies
thanku in advance :)
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