Mechanics | Relativity Answers

What is the angular momentum of a figure skater spinning at 3.06 rev/s with arms in close to her body, assuming her body to be a uniform cylinder with a height of 1.55m, a radius of 15.2cm ,and a mass of 49.6kg?
Calculate the torque required to slow her to a stop in 3.82s, assuming she does not move her arms?

A hawk is hunting and sees a mouse 100 m away. The hawk catches the mouse in
12.2s. The speed of the hawk was recorded at 35.8 m/s. What was the rate of
acceleration?

An echo is heard in 3s.what is the distance of the reflecting surface from the source,given that the speed of sound is 342m/s

A bus starts from rest with a constant acceleration of 5 m/sec Square. at the same time a car travelling at a constant velocity of 50m/sec overtakes the Bus and passes it. find at what distance will the bus overtake the car and how fast the bus would be travelling then

A flywheel has a moment of inertia of 1.6 × 10−3 kg.m2. When a constant torque is applied, it reaches an angular velocity of 1200 rev/min in 15 s. Assuming it started from rest, find:
i) the angular acceleration
ii) the unbalanced torque applied
iii) the angle turned through 15 s
iv) the work done on the flywheel by the torque

a) John is riding a bicycle and comes across a hill of height 7.30 m. At the base of the hill, he is traveling at 6.00 m/s. When he reaches the top of the hill, he is traveling at 1.00 m/s. Jonathan and his bicycle together have a mass of 85.0 kg. Ignore friction in the bicycle mechanism and between the bicycle tires and the road.
i) What is the total external work done on the system of Jonathan and the bicycle between the time he starts up the hill and the time he reaches the top?
ii) What is the change in potential energy stored in Jonathan’s body during this process

In the system shown, a horizontal force Fx = 40 N acts on an object of mass m2 = 8.00 kg. A friction force fk = 5 N acts between object m2 and the table top, and m1 = 2.00 kg.
i) Calculate the acceleration of the masses.
ii) Calculate the tension in the string

A body is in simple harmonic motion with time period T=0.5s and amplitude A=1cm. Find the average velocity in the interval in which it moves from equilibrium position to half of its amplitude.
Ans 12cm/s

Chad and Tara go for a ride on a merry-go-round. Chad sits on a pony that is 2.0 m from the rotation axis, and Tara sits on a pony 4.0 m from the axis. The merry-go-round is traveling counterclockwise and is speeding up. Does Chad or Tara have (a) the larger linear speed? (b) the larger centripetal acceleration? (c) the larger tangential acceleration?

A mass attached to a light spiral is caused to perform simple harmonic motion of frequency F=1÷2Π√k÷m where k is the force constant of the spring. 2.Explain the physical significance of k ÷m.