Mechanics | Relativity Answers

if a ball is fall on ground from a table , then the work done by gravitational force= mgh.?
when any agent do this it becomes= (-mgh). why it is negative here?please explain

A moon worm is orbiting an asteroid in a circular path with radius r and speed v. If the moon worm decides to double its speed, how will it have to change the radius of its path so that it continues to orbit the asteroid in a perfect circle?

a ball is hit with 20 m/s velocity creating an angle of 30 degree.it is dropped after some time.6 s after dropping, one fielder took the ball and threw it .at that moment a batsman achieves 1 run and started running for the 2nd run.after 3 s from throwing time , the ball hits the stump.to complete 1 run a batsman need minimum 6 s. will the batsman got run out ??

a ball is hit with 30 m/s velocity creating an angle of 20 degree.at the place , where the ball reaches it's maximum height, at that point a fielder who is 5 feet and 8 inches tall is fielding.he jumps 2 m high to catch the ball.the distance of the boundary is 70 m from the hitting place.and another fielder is fielding inside 11 m from boundary .

a) will the 1st fielder be able to catch the ball??

b)if the 1st fielder fails to take the catch by any chance , will the 2nd fielder be able to take the catch?

c) does the height of the 1st fielder is necessary to solve part a) ??

Weights are tied to each end of a 20.0cm string. You hold one weight in your hand and let the other hang vertically a height h above the floor. When you release the weight in your hand, the two weights strike the ground one after the other with audible thuds. Find the value of h for which the time between release and the first thud is equal to the time between the first thud and the second thud

A ball is hit with 30 m/s velocity creating an angle of 20 degree. At the place , where the ball reaches it's maximum height, at that point a fielder who is 5 feet and 8 inches tall is fielding. He jumps 2 m high to catch the ball.the distance of the boundary is 70 m from the hitting place. And another fielder is fielding inside 11 m from boundary .

a) will the 1st fielder be able to catch the ball??

b)if the 1st fielder fails to take the catch by any chance , will the 2nd fielder be able to take the catch?

c) does the height of the 1st fielder is necessary to solve part a) ??

A ball is hit with 20 m/s velocity creating an angle of 30 degree. It is dropped after some time. 6 s after dropping, one fielder took the ball and threw it. At that moment a batsman achieves 1 run and started running for the 2nd run. After 3 s from throwing time, the ball hits the stump. To complete 1 run a batsman need minimum 6 s. Will the batsman got run out ?

A ball is hit with 30 m/s velocity creating an angle of 20 degree. At the place , where the ball reaches it's maximum height, at that point a fielder who is 5 feet and 8 inches tall is fielding. He jumps 2 m high to catch the ballm the distance of the boundary is 70 m from the hitting place, and another fielder is fielding inside 11 m from boundary.

a) will the 1st fielder be able to catch the ball??

b)if the 1st fielder fails to take the catch by any chance , will the 2nd fielder be able to take the catch?

c) does the height of the 1st fielder is necessary to solve part a) ??

How much force is needed to lift a 10.0 kg mass from a horizontal position using
the human arm if the forearm is 25 cm long and the lifting muscle is 2.0 cm from
the elbow?

Three identical particles are joined together by a thread as shown in the figure. All the three particles are moving on a smooth surface horizontal plane about point O. If the speed of the outermost particle is V, then the ratio of tensions in the three sections of the string is: ( Assume that the string remains straight)

• ------------- • ------------ • ------------ •
O A B C
(1)3:5:7
(2)3:4:7
(3)7:11:6
(4)3:5:6
(Hint: the distance between each point is l)