Question

(i) What type of motion is represented by OA, AB and BC?

(ii) What is the acceleration of the car?

(iii) What is the retardation of the car?​

Answer 1

$\LARGE{ \underline{ \red{ \sf{Required \: answer:}}}}$

We are provided with a speed-time graph of speed as the dependent variable and time as the independent variable. We have to answer some questions by analysing the given graph.

[1] (I) Motion shown in OA

• The graph is a straight line inclined at some angle and the speed is gradually increasing. So, this is a Non-uniform motion with uniform accleration.

Motion shown in AB

• The Initial and final speed for this part is same. It is a straight line parallel to the time axis. Hence, this is an uniform motion with 0 accleration.

Motion shown in BC

• The initial speed is more than the final speed and it is a straight line. The speed is gradually decreasing which means it is a Non-uniform motion with uniform retardation.

━━━━━━━━━━━━━━━━━━━━

(II) The accleration of the car is given from O to A where the initial speed is 0 m/s and final speed is 40 m/s. The time taken to reach the final velocity is 20s. By using formula:

$\large{ \cdot{ \boxed{ \rm{a= \frac{v - u}{t} }}}}$

Plugging the values of v, u and t to find the accleration of the car:

⇛ a = 40 - 0 / 20 m/s²

⇛ a = 40 / 20 m/s²

⇛ a = 2 m/s²

━━━━━━━━━━━━━━━━━━━━

(III) The retardation can be seen from B to C. The initial speed is now 40 m/s and the final speed is 0 m/s. The time taken to stop is 20s. By using formula,

⇛ a = 0 - 40 / 20 m/s²

⇛ a = -40 / 20 m/s²

⇛ a = -2 m/s²

❒ Retardation is negative accleration. So, the retardation of the car that can be seen from B to C is 2 m/s²

And we are done!!

Answer 2

Answer:-

(i) What type of motion is represented by OA, AB and BC?

Answer:-

➤ OA represents uniform acceleration.

➤ AB represents constant speed.

➤ BC represents uniform retardation.

(ii) What is the acceleration of the car?

Answer:-

Acceleration formula = v - u/t.

Here,

v = 40m/s

u = 0m/s

t = 20s

↦ 40 - 0/20

↦ 40/20

↦ 4/2

↦ 2m/s²

(iii) What is the retardation of the car?

Answer:-

Retardation occurs from B to C.

Here,

v = 0m/s

u = 40m/s

t = 20s

↦ 0 - 40/20

↦ -40/20

↦ -2m/s²