Q37. What do you understand by state of Motion?
Q38. Why the tools meant for cutting and piercing always have sharp edges?
Q39. Explain why, the tip of a sewing needle is sharp.
Q40. “When a ball is dropped from a height, its speed increases gradually.” Name the force which causes this change in speed.
Q41. Explain why, porters place a thick, round piece of cloth on their heads when they have to carry heavy loads.
Q42. Explain now why shoulder bags are provided with broad straps and not thin strap?
Why the straps of school bags are made broader?
Why is it comfortable to lift a school bag with broad straps than thin straps?
Q43. A small device pulls iron nails from a distance. Which type of force is involved in this process?
Q44. Write one example where force changes the direction of a moving object.
Q45. Explain why, frictional force is said to be a contact force.
Q46. In a tug of war; when the two teams are pulling the rope, a stage comes when the rope does not move to either side at all. What can you say about the magnitudes and directions of the forces being applied to the rope by the two teams at this stage?
Q47. Explain why the walls of a dam are thicker near the bottom than at the top.
Q48. Give three examples of non-contact forces.
Q49. A rocket has been fired upwards to launch a satellite in its orbit. Name the two forces acting on the rocket immediately after leaving the launching pad.
Q50. What is meant by gravitational force (or force of gravity)? Give its one example.