Question

a car starts from rest and moves with constant acceleration of 4 m/s for 30 seconds.Then the brakes are applied and the car comes to rest in another 60 seconds.find maximum velocity attained by car

Answer 1

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\tt{\therefore{Maximum\:velocity=120\:m/s}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\green{\underline \bold{Given :}} \\ \tt: \implies Acceleration(a) = 4 { \: m/s}^{2} \\ \\ \tt: \implies Time(t) = 30 \: sec \\ \\ \red{\underline \bold{To \: Find:}} \\ \tt: \implies Maximum \: velocity =?$

• According to given question :

$\tt \circ \: Initial \: velocity = 0 \: m/s \\ \\ \bold{As \: we \: know \: that} \\ \tt: \implies v = u + at \\ \\ \tt: \implies v = 0 + 4 \times 30 \\ \\ \tt: \implies v = 0 + 120 \\ \\ \green{\tt: \implies v = 120 \: m/s}$

• After 30 seconds the velocity get start decreasing due to applied of brake on car.

$\green{ \tt \therefore Maximum \: velocity \: attained \: is \: 120 \: m/s}$

Answer 2

Aɴꜱᴡᴇʀ

$\large\tt\pink{{}v_{max} = 120 \: m/s}$

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Gɪᴠᴇɴ

✭ Initial velocity (u) = 0 m/s

✭ Acceleration (a) = 4 m/s²

✭ Time (t) = 30 seconds

✭ Final velocity (v) = 0 m/s

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Tᴏ ꜰɪɴᴅ

➤ Maximum velocity of the body?

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Sᴛᴇᴘꜱ

❍ Actually if you see the question carefully, we need not calculate any quantity that is should be found with the information that the car comes to a stop after 60 seconds ( These things are just added to confuse us). So we need not take that into any of our calculation.

So the Velocity of the body can be found with the help of the first law of motion, that is,

$\large \underline{ \boxed{ \sf{v = u + at}}}$

Substituting the given values,

$\large \tt \dashrightarrow{} v_{max} = 0+4\times30 \\ \\ \large\tt\dashrightarrow{} v_{max }= 4\times30 \\ \\ \large\tt\red{\dashrightarrow{}v_{max} = 120 \: m/s}$

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