Mechanics | Relativity Answers

Rock A is dropped straight down. After 2 seconds, Rock B is dropped straight down as well. As both rocks are falling, will the separation distance between Rock A and B increase, decrease or stay the same?

A dog weighing 5.0 kg is standing on a flatbed boat so that he is 20.0 m from the shore. He walks 8.0 m on the boat toward the shore and then stops. The boat has a mass of 20 kg, and one can assume there is no friction between it and the water. How far is he from the shore at the end of his walk? Why?

a boy of is sitting on the horizontal platform of a joy wheel at a distance of 5m from the centre.the wheel begin to rotate and when the angular speed exceeds 1rad/s the boy slips.the coefficent of friction between the boy and the wheel is(g=10)
1. 0.5
2. 0.32
3. 0.71
4. o.2

a rocket of mass 5700kg ejects mass at a constant rate of 15kg/s with constant speed of 12km/s.the acceleration of the rocket 1 minute after the blast is (g=10m/s2)
1.34.9m/s2
2.27.5m/s2
3.3.50m/s2
13.5m/s2

two forces of 10N and 6N act upon a body.the direction of the forces are unknown.the resultant force on the body
1.15N
2.3N
3.17N
4.2N

(Ill) Many sailboats are moored at a marina 4.4km away on the opposite side of a lake. You stare at one of the sailboats because, when you are lying flat at the water’s edge, you can just see its deck but none of the side of the sailboat. You then go to that sailboat on the other side of the lake and measure that the deck is 1.5m above the level of the water. Using Fig. 1-12, where h = 1.5 m, esti­mate the radius R of the Earth.

a student runs 2 laps around a track in 120 seconds. The distance around the track is 400 meters. What is the student's velocity for the run? what is the student's average speed forthe trip?

An alloy containing 80 parts of tin and 15 parts of antimonyby weight weighs 190 gm. Find the volume of thr alloy given specific gravity of tin and antimony are 7.3 and 6.6 respectively.

A pulley system with 76% efficiency is set up to lift a 18kg bag of nails. The bag is lifted to a height of 2.1m by a person pulling on the rope with a force of 58.0N.

3) What is the actual mechanical advantage of this pulley system?


4) What is the ideal mechanical advantage of this pulley system?


5) What is the distance the rope must be pulled in order to lift the bag of nails?

A pulley system with 76% efficiency is set up to lift a 18kg bag of nails. The bag is lifted to a height of 2.1m by a person pulling on the rope with a force of 58.0N.

1) What is the work done on the bag of nails by the pulley?


2) How much work is input to the system?