Question

24. It is easier to cut with a sharp knife than with a
blunt one. Explain.
25. A gum bottle rests on its base. If it is placed
upside down, how does the (i) thrust, (ii) pressure
change?
26. Explain the following:
9. Write the expression for the moment of force
about a given axis of rotation.
(a) Sleepers are used below the rails.
(b) A tall building has wide foundations.
10. State one way to decrease the moment of a given
force about a given axis of rotation.
27. Describe an experiment to show that a liquid
exerts pressure at the bottom of the container in
11. State one way to obtain greater moment of a given
which it is kept.
force about a given axis of rotation.
28. Describe a suitable experiment to demonstrate that a liquid exerts pressure sideways also
29. Describe a simple experiment to show that at a given depth a liquid exerts same pressure in all directions
14. What is thrust?
15. State the unit of thrust.
16. On what factors does the effect of thrust on a
surface depend ?
17. Define the term 'pressure and state its unit.
18. How is the thrust related to pressure ?

19. Name two factors on which the pressure on a
33. Describe an experiment to show that liquid
surface depends.
pressure depends on the density of liquid.
20. When does a man exert more pressure on the
34. A dam has broader walls at the bottom than at
floor : while standing or while walking ?
the top. Give a reason.
21. Why do camels or elephants have broad feet?
35. What do you mean by atmospheric pressure ?
22. A sharp pin works better than a blunt pin. Explain
36. Write the numerical value of the atmospheric
the reason.
pressure on the earth surface in pascal.
23. Why is the bottom part of the foundation of a
37. We do not feel uneasy even under the enormous
building made wider ?
atmospheric pressure. Give a reason.

Answer 1

Answer:

24.because the sharp knife has less surface and it creates more pressure