Question

a bike initially at rest picks up a velocity of 20 km/hr over a distance of4000m. Calculate (1) acceleration (ii) time in which it picks up a velocity​

Answer 1

Given:

• A bike initially at rest picks up a velocity of 20 km/hr over a distance of 4000m.

To Calculate:

• (i) Acceleration.
• (ii) Time in which it picks up a velocity.

Step-by-step explanation:

We have,

Initial velocity, u = 0 m/s

Final velocity, v = 20 km/h

Distance, S = 4000 m = 4000/1000 km

Distance, S = 4 km

Using third equation of motion,

♦ v² - u² = 2aS

Putting the values,

• 20² - 0² = 2 × a × 4
• 400 - 0 = 2 × a × 4
• 400 = 8 × a
• a = 400/8
• a = 100/2
• a = 50 km/h² ≈ 0.0038 m/s²

Therefore,

Acceleration of a bike = 50 km/h² ≈ 0.0038 m/s²

Using first equation of motion,

♦ v = u + at

Putting the values,

• 20 = 0 + 50 × t
• 20 = 50 × t
• t = 20/50
• t = 2/5
• t = 0.4 h = 1140 sec

Therefore,

Time in which it picks up a velocity = 0.4 h = 1140 s

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