Question

SECTION A

1. Differentiate between speed and velocity. (1)
2. Which law of motion gives the measure of force? Write an expression for force. (1)
3. Name the principle on which a rocket works. (1)
OR
Why does a boat tend to leave the shore, when passengers are alighting from it?
4. (1)
If the small and big stones are dropped from the roof of a house simultaneously, they will reach the
ground at the same time. Why?
5. The distance between two objects is decreased. Will the gravitational force between them increases (1)
or decrease?
6. What is the SI unit of acceleration due to gravity (g)? (1)

OR
What is the SI unit of gravitational constant G?

Answer 1

Answer:

1) Speed is the time rate at which an object is moving along a path, while velocity is the rate and direction of an object's movement. Put another way, speed is a scalar value, while velocity is a vector.

2) Newton's second law of motion

Newton's second law of motion gives the quantitative measurement of force; F = ma.

3) conservation of momentum

The rocket operates on the principle of conservation of momentum.

4)If the small and big stones are dropped from the roof of a house simultaneously, they will reach the ground at the same time. Why? Answer: The acceleration due to gravity does not depend upon the mass of the stone or body.

5) Since gravitational force is inversely proportional to the square of the separation distance between the two interacting objects, more separation distance will result in weaker gravitational forces. So as two objects are separated from each other, the force of gravitational attraction between them also decreases.

6) newtons per kilogram

The gravity of Earth, which is denoted by g, refers to the acceleration that the Earth imparts to objects on or near its surface. In SI units this acceleration is measured in metres per second squared (in symbols, m/s2) or equivalently in newtons per kilogram (N/kg).

or

Newtons kg

In SI units, G has the value 6.67 × 10-11 Newtons kg-2 m2. The direction of the force is in a straight line between the two bodies and is attractive. Thus, an apple falls from a tree because it feels the gravitational force of the Earth and is therefore subject to “gravity”.