CBSE Class 8 Science Question 2 of 2

Exploring Forces — Question 10

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10
Question
Three objects, 1, 2, and 3 of the same size and shape but made of different materials, are placed in the water. They dip to different depths as shown in the figure.If the weights of the three objects 1, 2, and 3 are w1, w2, and w3, respectively, then(i) w1 = w2 = w3(ii) w1 > w2 > w3(iii) w2 > w3 > w1(iv) w3 > w1 > w2Answer:(ii) The relationship between the weights of the objects is w1 > w2 > w3Object 1 is the deepest meaning it displaces the most water.Object 2 is less deep than object 1 but deeper than object 3.Object 3 is the least deep, meaning it displaces the least amount of water.Since the objects have the same size and shape, the greater the depth, the greater the weight of the object (assuming they are all made of the same material).Hence, the object with the greatest weight will sink the deepest, and the object with the least weight will be the closest to the surface.
Answer

[Exploring Forces Class 8 Questions and Answers Science Chapter 5 Activity Q1]
Answer:
Yes, the object will stop after moving a certain distance when pushed on a table or floor. This is due to the force of friction, which opposes the motion of the object and eventually brings it to rest. When the object is pushed in the opposite direction, it will again stop after a certain distance due to the same frictional force.

Activity 5.8: Let Us Observe (Page 71)

  • Take a ball and throw it vertically upwards. Does it come down?
  • Now throw it again, but this time harder. Does it still fall back down to the ground?

Think about different situations around you where any object thrown up in any direction finally falls or comes back to the ground or floor.
[Exploring Forces Class 8 Questions and Answers Science Chapter 5 Activity Q2]
Answer:

  1. Throwing a ball upwards: When we throw a ball upwards, it will come back down to the ground.
  2. Throwing it harder: Even if we throw the ball harder, it will still fall back down. Throwing it harder simply gives it a greater initial upward velocity, allowing it to reach a higher point before gravity eventually overcomes that upward momentum and pulls it back down.

Different Situations
Many objects around us demonstrate this principle of gravity:

  • A thrown stone: Whether we throw a stone straight up or horizontally, it will always follow a curved path and eventually land on the ground due to gravity.
  • A dropped mango: A mango falling from a tree illustrates the same principle – gravity pulls it towards the Earth.
  • Raindrops: Raindrops fall from the clouds to the ground due to the Earth’s gravitational pull.