Question

A car starts from rest and accelerates with 2 m/s

2 for 10 s. After maintaining the

velocity for 10 seconds, it comes to rest decelerating by 1 m/s

2

. Find the total distance

travelled.​
plz help me its urgent plz

Answer 1

Answer:

Initial speed (U) = 0

Acceleration (A) = 2

Time (T) = 10

Final speed (V) = U + AT

                         = 0 + 10 x 2

                         = 20

Hence maximum velocity attained is 20 m/s

Deceleration (D) = -1

Initial velocity after 20 seconds = V = 20

Final velocity (V1) = 0

Time (T1) = (V1 - U) / D

                = (0 - 20) / (-1)

                = 20 seconds

Total distance travelled = Distance while accelerating + Distance while decelerating + Distance without acceleration

= (0.5 x 2 x 10^2) + (20^2 / 2 x 1) + (20 x 10)

= 100 + 200 + 200

= 500 metres

Maximum velocity attained is 20 metres/second

Maximum velocity attained is 20 metres/secondTotal distance travelled is 500 metres

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Answer 2

Given

● Car starts from rest.

● Acceleration = 2 m/s²

● Time taken = 10 seconds.

● Maintained constant velocity for 10 seconds.

● Comes to rest decelerating by 1 m/s²

To find

● Total distance travelled by car.

Solution

When car moving with constant acceleration :

Initial velocity (u) = 0 [∵Starts from rest]

Acceleration (a) = 2 m/s²

Time taken by car = 10 seconds.

Using 1st equation of motion :

★ v = u + at

⇒ v = 0 + 2 × 10

⇒ v = 20 m/s

∴ Final velocity of car = 20 m/s

Using 2nd equation of motion :

★ s = ut + ½ at²

⇒ s = 0 × 10 + ½ × 2 × 10²

⇒ s = 0 + 100

⇒ s = 100 m

∴ Distance travelled by car while moving with constant acceleration = 100 m.

_______________________

When car was moving with constant velocity :

Here initial velocity of car will be the final velocity of car while accelerating i.e. 20 m/s

Time = 10 s

As the car was moving with constant velocity,

★ Distance = Speed × Time

⇒ Distance = 20 × 10

⇒ Distance = 200 m

∴ Distance travelled by car whilr moving with constant velocity = 200 m

__________________________

When car was moving with deceleration :

Here initial velocity of car is final velocity of car while moving with constant velocity i.e. 20 m/s

As the car comes to rest, so final velocity i.e. v = 0 m/s

Deceleration = 1 m/s²

∴ Acceleration (a) = -1 m/s²

Using 1st equation of motion :

★ v = u + at

⇒ 0 = 20 + (-1)t

⇒ 20 - t = 0

⇒ t = 20 s

∴ Time taken by car to stop = 20 s

Using 2nd equation of motion :

★ s = ut + ½ at²

⇒ s = 20 × 20 + ½(-1) × 20²

⇒ s = 400 + ½(-1) × 400

⇒ s = 400 - 200

⇒ s = 200 m

∴ Distance travelled by car while moving with deceleration = 200 m

___________________________

Now total distance travelled by car :

★ Total distance = Distance (a) + Distance (v) + Distance (d)

⇒ Total distance = (100 + 200 + 200) m

⇒ Total distance = 500 m

∴ Total distance travelled by car = 500 m (Required answer)