Advertisements
Advertisements
Question
Why is a force needed to keep a block of wood inside water?
Advertisements
Solution
A force is required to hold a block of wood in water because the upthrust caused by water on the block when fully submerged surpasses its weight.
APPEARS IN
RELATED QUESTIONS
Name the scientist who gave he magnitude of buoyant force acting on a solid object immersed in a liquid.
The density of water is 1.0 g Cm-3. The density of iron is 7.8 × 10″3 g Cm-3. The density of mercury is 13.6 g Cm-3.
Ans the following:
Will a piece of iron float or sink in water?
What physical quantity is measured in bar?
Why is the tip of an allpin made sharp?
Why do sea divers need special protective suit?
How does the liquid pressure on a diver change if :
The diver moves horizontally?
The diagram below in Fig. 4.12 shows a device which makes the use of the principle of transmission of pressure.
- Name the parts labelled by the letters X and Y.
- Describe what happens to valves A and B and to the quantity of water in the two cylinders when the lever arm is moved down.
- Give reasons for what happens to valves A and B in part (ii).
- What happens when the release valve is opened?
- What happens to valve B in cylinder P when the lever arm is moved up?
- Give a reason for your answer in part (v).
- State one use of the above device.
Will a body weigh more in air or vacuum when weighed with a spring balance? Give a reason for your answer.
How is the upthrust related to the volume of the body submerged in a liquid?
Figure shows the same block of wood floating in three different liquids A, B and C of densities ρ1, ρ2 and ρ3 respectively. Which of the liquid has the highest density? Give a reason for your answer.
