Q1. What are the two conditions necessary for net force ?
Ans:
Q2. Which force is used in medical treatment and scientific research?
Ans: Magnetic Force
Q3. What is non-contact force and name their types also?
When a force is applied on some object by another object without any interaction or contact.
Types of non contact force
- Gravitational force
- Magnetic and electromagnetic force
- Electrostatic force
- Nuclear Force
Q4. Which force is used when you rub a balloon with your hair?
Ans: Electrostatic force.
Q5. Which force is used when the needle of compass acted towards North ?
Ans. Earth's Magnetic force
Q6. What are the uses of Nuclear forces?
Ans. Nuclear force can be used for both military and peaceful purposes. Nuclear force is used in medical treatment and scientific research.
Q7. Name the device used to measure blood pressure.
Ans: Sphygmomanometer
Q8. Why did cooked food takes more time at high places?
Ans: the atmosphere becomes much drier. The air has less oxygen and atmospheric pressure, so cooking takes longer.
Q9. Name the fluids present in our body.
Ans: Blood and lymph
Q10. Why do the mountaineers use oxygen cylinders while climbing the mountains?
Ans: As we climb to higher altitudes the amount of air decreases. And this lack of enough oxygen may cause suffocation to mountaineers when they reach high altitudes. So as a precaution mountaineers usually carry oxygen cylinders with them
Q11. How does air exerts pressure?
Ans: Air exerts pressure evenly in all directions.
Q12. In which direction liquids exert pressure?
Ans: Liquids exert pressure equally in all direction
Q13. Why did the water pressure in pond water more than in shallow lake?
Ans: The pressure exerted by water increases with depth. The water pressure at the bottom of a deep pond will be more than the water pressure at the bottom of a shallow lake, even if the lake is wider, spreads over a large area and contains more water.
Q14. What will be your mass if you are on moon?
Ans: Mass will remain the same as your weight changes according to the gravity.
QIS. What is the pressure exerted if we keep the book upright on its side, which measures 0.1m² o force 5 N?
Ans:
Q16. Sameer was moving a box. He used a force of 30 N to pull the box. His brother Karan helped by pushing the box towards him from other side with a force of 20 N. How much was the net force exerted?
Ans: Net Force = 30N + 20N = 50N
Q17. What are the effects of force? Describe them in your words with examples.
Ans. These are the following effects of force:
1. Force can get a stationary object to move, and a moving object to stop.
2. Force can change the speed of an object.
3. Force can change the direction of a moving object.
4. Force can change the shape of an object.
Q18. What is the SI unit of the following: a) Force b) Pressure
Ans: The SI units of Force and Pressure are N(Newton) and Pa(Pascal)
Q19. What is the difference between barometer and manometer?
Ans: A barometer is an instrument used to measure the air pressure as it varies with distance either above or below sea level. A manometer is used for measuring the liquid pressure with respect to an outside source which is usually considered to be the earth's atmosphere.
Q20. Write down the equation to calculate the pressure?
Ans: