What is the purpose of the spin cycle of a washing machine? Explain in terms of acceleration components.
The spin cycle in washing machine spins the clothes in the washing machine making them move circular. the continious circular motion by the spin cycle gives centripetal and pseudecentripetal ( centrifugal ) force. after the completion of wash, the centrifugal force generated makes the water in the clothes get extracted due to high force ( caused by acceleration due to the spin cycle ) and make clothes dry. so, it primarily acts as moisture absorbent.
How might you determine experimentally the moment of inertia of an irregularly shaped body about a given axis?
Using the parallel axis theorem
We note the angular speed and also the system energy. Using these information we calculate the moment of inertia of irregular shaped body.
When we have moment of inertia of irregular shaped body, we can then use parallel axis theorem to solve the moment of inertia if the body about the given axis.
To maximize the moment of Inertia of a flywheel while minimizing its weight, what shape and distribution of mass should it have? Explain.
We know that the moment of inertia of any rotating body is directly proportional to the square of the distance from its rotational axis. In the case of a flywheel, the position of an individual particle from the rotational axis matters for determining its moment of inertia. So, in order to maximize the moment of inertia, while minimizing its weight, we have to make a flywheel with the maximum possible radius while having gaps in the body, i.e. having spoke-like structures to hold the wheel. A...
An Olympic high diver starts his dive with a double somersault while keeping his arms neatly tucked to his chest. But as he approaches the pool surfaces, his arms stretch over his head to a point a...
I, personally loved this problem. Though I am not that much interested in playing sports on my own, I love the beauty of physics behind each sport, and the way physics beautifies each sport.
Before approaching the question, let's know how diving is scored in Olympic games. The judges score looking at the starting position, approach, height, flight, and entry. The higher jump with a maximum number of somersaults and a perfect entry with a minimal splash is always considered the best one.
A student stands on a table rotating with an angular speed while holding two equal dumbbells at arm's length. He pulls his hands towards him, what's its consequence? But now, without moving anythin...
The angular speed of the student will increase. When the dumbbells are dropped on the floor, no external torque acts on the student and the turntable, and therefore the angular momentum must be conserved.
When the dumbbells are dropped, the rotational inertia of the student and turntable decreased. To compensate for the decrease in rotational inertia the angular speed of the student and the turntable must increase.
An arrow turns in flight so as to be tangent to its flight path at all times. However, a football (thrown with considerable spin about its long axis) does not do this. Why this difference in behavior?
The initial angular momentum due to the spin in the football ensures that any angular momentum due to the action of external forces does not change the direction of the initial angular momentum significantly. This allows the ball to reach the catcher with the same orientation as it was when thrown by the passer.
In case of the arrow, the lack of initial spin allows external forces such as gravity to change the direction of the angular momentum vector. This is accomplished by moving the arrow...
Why it is much more difficult to balance yourself on a bicycle that is at rest than on one that is rolling?
Balance on a bicycle is a matter of constantly correcting against falls, and it's easier when thespeed is higher because the inertia of moving forward overcomes the need for corrective actions.
A helicopter flies off, its propellers rotating. Why doesn't the body of the helicopter rotate in the opposite direction?
In the air, there's nothing holding the body of the helicopter still - so the rotor blades spin one direction, butthe torque applied to spin the rotors tries to spin the bodyof the helicopter in the opposite direction. The little rotor on the tail helps keep the body of the helicopter pointed in the same direction.
Explain in terms of angular momentum and rotational inertia, exactly how one "pumps up" a swing in the sitting position.
When one sits in the sitting position, the rotational inertia of the body decreases. Since no external torque acts on the swing during this, the change of angular momentum must be conserved. To ensure this, the decrease in rotational inertia of the body must be compensated by increase in angular velocity, and the increased angular velocity eventually pumps up the swing.
A cylinder of radius R and mass M, rolls without slipping over the step as shown below. For cylinder-step system, which of the following quantities are not conserved?
A bicycle wheel is rolling on a level surface. At any given instant in time the wheel.
which way angular velocity point for the earth?
About what axis would a uniform cube have its minimum rotational inertia?
A ladder is at rest with its upper end against a wall and its lower end on the ground. A worker is about to climb it. When is it more likely to slip?
In one of his many action movies Jackie Chan jumped off a building by wrapping a rope around his waist and then allowed it to unwind as he fell to the ground, much the same as a yo-yo. Assuming his acceleration toward the ground was a constant much less than g, the tension in the rope would be
A particle moves with constant velocity v. The angular momentum of this particle about the origin is zero
The linear velocity v and linear momentum p of a body (Note: Bold represents it is vector)
The angular velocity and angular momentum of a body with axial symmetry
A body, not necessarily rigid, is originally rotating with angular velocity of magnitude ω and angular momentum of magnitude L. Something happens to the body to cause ω to slowly decrease. Consequently,
A solid object is rotating freely without experiencing any external torques. In this case,
Two independent particles are originally moving with angular momenta l and L in a region of space with no external torques. A constant external torque τ then acts on particle one, but not on particle two, for a time t, what is the change in the total angular momentum of the two particles?
In rotational motion, the physical quantity that imports angular acceleration is
If L represents momentum, I represents the moment of inertia, then (L^2)/2I represents
Which of the following is a correct formula for calculating the radius of gyration K of a rotating object?
Radius of gyration of a uniform rod of length L about an axis through its middle is
When torque acting upon a system is zero, which of the following will be constant?
A fun makes 10 revolutions in 3 sec, which is just switched on. Considering uniform acceleration, the number of revolutions made by the fan in the next 3 s is
The spokes are used in the bicycle wheel to
The moment of inertia does not depend on
If no internal force is applied to a body, the velocity of the center of mass
The moment of inertia depends on
The torque due to the gravitational force on a body about its center of mass is
The center of gravity of a body
the ratio of angular velocity of the earth about its axis to the hour hand of the clock is
The radius of the earth's orbit is made one fourth, the duration of the year will become
If the is a chance of angular momentum from 2J to 4 J in 4s , the torque is
The ratio of the angular speeds of the minute hand and hour hand of a clock is