Mechanics | Relativity Answers

A pump can empty a 7.5 m deep and 0.9 m radius well in 30 mints.but the pump got damaged after emptying half of the well.?
a pump can empty a 7.5 m deep and 0.9 m radius well in 30 mints.but the pump got damaged after emptying half of the well. then another pump is used to empty the rest which can empty it in 15 mints.what is the ratio of the power of the two pump?

for the 2nd pump the time given here is it the time for emptying whole well or emptying the rest after the 1st one damaged?

if a 3 m deep well is half filled with water, then how much time needed to raise 2 kg water with a 10 kw pump whose efficiency is 70%?

a fulfilled well is 10 m deep and has a radius of 4 m.a 6.87 H.P pump is used to empty the well in 20 minutes. but after emptying half of the well, it got damaged. after how much time the pump got damaged? if another pump is used to empty the rest of the well in the limited time,will the power of the 2nd pump be same of the 1st one? mathematically explain

a stair is at 60 degree angle with roof. a man of 60 kg with 20 kg bag is using stair to go to roof. how much work he does?if he used the stair perpendicularly , how much work he did?

does both work same??
if same then why?

A bullet loses (1/n) th of its velocity when it passes through one plank. How many such planks are required to stop the bullet ?

a man is moving with a 1500 kg car on a hilly road with 25 m/s velocity.the road creates an angle with ground 30 degree.but seeing a tree the car stops the car at 50m.what is the frictional force to stop the car?use work energy theorem

a pump can work 3.403 kJ per second in 70% efficiency. a motor is used to run the pump.efficiency of motor is 85%, what is the actual power of the pump?

Consider a wave represented as y(x, t) =2sin(10πt - πx/40+π/4) .Plot the space profile at t=T/4 and time profile at x= λ/8.

gravitational force work downward. if a ball is placed on a table from ground , then the work done by gravitational force= -mgh. when any agent do this it becomes =mgh. why it is positive here?

how does gravitational force work in 1st case without external agent?is it possible?

A ball is thrown upward . at what height it's kinetic energy will be twice of it's potential energy?