Mechanics | Relativity Answers

If the coefficient of static friction is 0.23 and the coefficient of kinematics friction is 0.18 what force is required to start a 8.6 kg object moving ?

Free neutrons of mass, 1.67 × 10–27 kg and de Broglie wavelength 1 nm have a mean life
time of about 900 s. The distance from the source where the number of neutrons have
decayed to one-half its initial value is (h = 6.62 × 10–34 Js)
(1) 2.4 × 105 m (2) 2.4 × 10–4 m
(3) 4.8 × 105 m (4) 4.8 × 10–4 m

The pilot of the airplane which has been diving at a speed of 540 km/h pulls out of the dive following a circular path at a constant speed.
- What is the minimum radius of the planes circular path in order that the acceleration of the pilot at the lowest point not exceed 7G?
- What is the apparent weight of an 80.0kg pilot at the lowest point of the pullout.

A Ring of radius R is first rotated with an angular velocity ∆ and then carefully placed on a horizontal rough surface. The coefficient of friction between the surface and the ring is ¶. Time after which its angular speed is reduced to half is

Prove that in ∆=r^2 cotalpha/2 cot beta/2 cot gamma/2

If light travels for 7.2 minutes, how many meters does it travel?

Two objects are involved in a collision. The first object, of mass 12 kg slows from 8 m s-1 to zero on 0.5 s applying its force to the second object which has a mass of 10 kg. Calculate:
a) the acceleration to the first object.
b) the force applied to the second object.
c) the acceleration of the second object during the collision.

An athlete runs 100m in 12s. What is his speed in km/hr?

The tension in a rope pulling a log is 100N, the mass of the log is 50kg and the frictional force on the log is 20N. What is the acceleration of the log?

A ball is thrown vertically upwards with a velocity of 40m/s. Find the greatest height attained.