Question

A car travelling at 20m/s collides with a stationary lorry and stops completely in just 0.02s. Calculate the deceleration of the car.​

Answer 1

Answer

• The deceleration of the car is 1000 m/s²

Explanation

Given

• Initial Velocity = 20 m/s
• Final Velocity = 0 m/s
• Time = 0.02 sec

To Find

• The deceleration of the car

Solution

● Here we shall use the first equation of motion as we are given the initial & the final velocity along with the time taken. And here eventhough the acceleration would be negative, the answer would be positive as we have to find tye deceleration (Negative Acceleration)

● v = u+at

✭ Deceleration of the Car

→ v = u+at

→ 0 = 20 + a × 0.02

→ -20 = 0.02a

→ -20/0.02 = a

→ Deceleration = 1000 m/s²

∴ The car would have deceleted at a rate of 1000 m/s²

Know More

• s = ut + ½at²
• v² - u² = 2as

Answer 2

♣ɢɪᴠᴇɴ:–

• Initial velocity (u) = 20 m/s

• Final velocity (v) = 0 m/s

• Time (t) = 0.02 s

♣ᴛᴏ ғɪɴᴅ:–

• Deceleration of the car = ?

♣sᴏʟᴜᴛɪᴏɴ:–

➤ Since we have been provided both initial and final velocity and time we can use the first equation of motion to find the deceleration of the car.

➤ Even if the acceleration comes in negative we will have the deceleration as negative as it is negative acceleration.

• v = u + at

⇒ 0 = 20 + (a × 0.02)

⇒ 0 - 20 = 0.02a

⇒ -20 = 0.02a

⇒ a = -(20/0.02)

⇒ a = -(2000/2)

⇒ a = -1000

➠ Deceleration = 1000 m/s²

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♣ᴀɴsᴡᴇʀ:–

• The deceleration of the car is 1000 m/s²