Question

A car initially traveling at 54 km/hr slows down uniformly to a velocity of 18 km/hr when the brakes were gradually applied. How long does it take to cover a distance of 50 meters?

A) 5 seconds
B) 8 seconds
C) 10 seconds
D) 12 seconds

Answer 1

The car takes 5 seconds to cover a distance of 50 meters when it slows down from an initial velocity of 54 km/hr to a final velocity of 18 km/hr.

Step-by-step explanation:

To find the time it takes for the car to cover a distance of 50 meters, we need to use the equation of motion for uniformly decelerating motion. First, we need to convert the initial velocity and final velocity from km/hr to m/s.

Initial velocity = 54 km/hr = 54 × (1000/3600) m/s = 15 m/s

Final velocity = 18 km/hr = 18 × (1000/3600) m/s = 5 m/s

Next, we can use the equation:

Final velocity = Initial velocity + acceleration × time

Solving for time:

Time = (Final velocity - Initial velocity) / acceleration

Substituting the given values:

Time = (5 m/s - 15 m/s) / (-2 m/s²) = -10 m/s / -2 m/s² = 5 seconds

Therefore, it takes 5 seconds for the car to cover a distance of 50 meters.