Question Text
Question 2 :
When a body is partially or completely immersed in a fluid at rest, it experiences an upthrust which is equal to the weight of the fluid displaced by it.
Question 3 :
Assertion: A balloon filled with hydrogen stops rising after it has attained a certain height in the sky.
Reason: As height increases, the density of air decreases resulting in an increase of buoyant force.
Question 4 :
A boat floating in fresh water displaces $16,000\ N$ of water. How many newtons of saltwater would it displace if it floats in saltwater of specific gravity $1.17$?<br>
Question 5 :
The acceleration of free fall on Pluto is $0.66m s^{-2}$. An object weighs $6.0$N on Earth. What would this object weigh on Pluto?
Question 6 :
A man can lift a block of mass of 50 kg up to a height of 2 m in 2 seconds. Calculate the power developed by the man to lift the block.
Question 8 :
A man starts walking from a point on the surface of earth (assumed smooth) and reaches diagonally opposite point. What is the work done by him:
Question 9 :
A man weighing $60\ kg$ climbs up a staircase carrying a load of $20\ kg$ on his head. The stair case has $20$ steps each of height $0.2\ m$. If he takes $10\ s$ to climb, find his power.
Question 10 :
An engine lifts $2250$ litres of water per minute from a well $20 m$ deep. If $25$ % energy of the engine is wasted, the power to be given to the engine must be (Take $g=9.8 \ m/s^2$)