Question

A truck driver travelling at 36 km/h sees the traffic light
turn red at the intersection. If his reaction time is 0.6 s
and truck retards at 6 m/s2, then distance travelled by
truck before stopping is

(a) 8.33 m
(b) 16 m
(c) 10.22 m
(d) 14.33 m

Answer 1

Answer:

• Option (a) 8.33 m is the required answer .

Explanation:

Given:-

• Initial velocity ,u = 36km/h = 36×5/18 = 10m/s

• Final velocity ,v = 0m/s

• Time taken ,t = 0.6 s

• Retardation ,a = 6m/s²

To Find:-

• Distance travelled ,s

Solution:-

We have to calculate the distance covered by the truck . Using 3rd Equation of Motion

❒• v² = u² +2as

where,

• v is the final velocity
• a is the acceleration
• u is the initial velocity
• s is the distance travelled

Substitute the value we get

→ 0² = 10² + 2 × (-6) × s

→ 0 = 100 + (-12) × s

→ -100 = -12×s

→ s = -100/-12

→ s = 100/12

→ s = 8.33 m

• Hence, the distance travelled by the truck is 8.33 metres .

Answer 2

Answer:

Given :-

• A truck driver travelling at 36 km/h sees the traffic light turn red at the intersection. The time is 0.6 seconds and truck retards at 6 m/s².

To Find :-

• What is the distance travelled by the truck.

Formula Used :-

★ v² = u² + 2as ★

Solution :-

First, we have to find the initial velocity,

↦ 36 km/h

↦ 5 ÷ 18 × 36

➠ 10 m/s

Now, we get,

• Initial velocity = 10 m/s
• Final velocity = 0 m/s
• Time = 0.6 seconds
• Acceleration = 6 m/s²

According to the question by using the formula we get,

⇒ (0)² = (10)² + 2(6) × s

⇒ 0 = 100 + 12 × s

⇒ 0 - 100 = 12s

⇒ - 100 ÷ - 12 = s

⇒ 8.33 = s

➠ s = 8.33 m

∴ The distance travelled by truck is 8.33 m .

Hence, the correct options is option no (a) 8.33 m ✔