Question 1

Which of the following is a scalar quantity?

Accepted Answer

Scalar quantities are those quantities that have magnitude only and no direction. Among the given options, speed has only magnitude (e.g., 40 km/h) and no specific direction, whereas displacement, velocity, and acceleration are vector quantities because they require both magnitude and direction to b

Question 2

Rate of change of displacement is known as:

Accepted Answer

Velocity is defined as the displacement of an object per unit of time. Mathematically, it is the rate of change of displacement. Since displacement is a vector quantity, velocity is also a vector quantity, having both magnitude and direction.

Question 3

SI unit of acceleration is:

Accepted Answer

Acceleration is defined as the rate of change of velocity with respect to time. The SI unit of velocity is metre per second (m/s) and the SI unit of time is second (s). Therefore, the SI unit of acceleration is metre per second squared, written as m/s².

Question 4

From the given velocity-time graph, the area enclosed by the velocity-time graph and the time axis represents:

Accepted Answer

The area under a velocity-time graph represents the product of velocity and time. Since velocity multiplied by time gives displacement, the area enclosed by the velocity-time graph and the time axis gives the displacement of the object.

Question 5

Slope of a distance-time graph gives:

Accepted Answer

The slope of a distance-time graph is calculated by dividing the change in distance on the y-axis by the change in time on the x-axis. Since distance divided by time is speed, the slope of a distance-time graph represents the speed of the moving object.

Motion — CBSE Class 9 Science Important Questions & Revision Notes