Question

What is the difference between speed and velocity and acceleration?

Answer 1

Hint: These three terms are related to kinematics, whole kinematics depends on these terms only. All these terms are interrelated to each other and each of these terms has their important significance in study of motion and rest of the body. These terms also explain the clear example of scalars and vector quantity.

Complete step-by-step solution:
These terms are interrelated to each other and related to kinematics but they have some differences. These differences are as follows: -
1. Definition: - Speed is defined as distance travelled per unit time while Velocity is defined as rate of change in displacement with respect to time and acceleration is defined as rate of change in velocity with respect to time.
2. Speed is a scalar quantity because it shows only the magnitude while velocity and acceleration are vector quantities because they show magnitude with direction. Magnitude of velocity is called speed.
3. For a moving body speed is always positive while for moving body velocity and acceleration can be negative, positive and zero also.
4. Speed is measured by a device called speedometer while velocity and acceleration cannot be measured by this device.
5. S.I Unit of Speed and velocity is same as \[\dfrac{m}{s}\] while S.I unit of acceleration is\[\dfrac{m}{{{s}^{2}}}\].
6. Dimension of speed and velocity is the same as \[[L{{T}^{-1}}]\] while dimension of acceleration is\[[L{{T}^{-2}}]\].
7. The ratio of total distance with total time gives the average speed of the body while ratio of total change in displacement with time gives the information about average velocity and ratio of total change in velocity with time gives the information about average acceleration.
8. For moving, body speed is always greater than or equal to velocity. When acceleration becomes positive it means velocity is increasing and when acceleration is negative it means velocity is decreasing, negative acceleration is called retardation or deceleration.

Note: To solve numerical problems based on these we will use direct formulas or equations of motion. Rate of change of acceleration with respect to time is defined as jerk. Whenever acceleration is not uniform you will feel jerk. This shows that acceleration is changing with respect to time. This is also defined as the significance of the acceleration time graph.