Question

2. You are traveling along a highway at night at a speed of 100 km/h when you spot an object directly in front of you in the road at the limit of your headlights. (10 Marks)

a) If the maximum braking deceleration that your car can provide is 7 m/s2, and if your headlights extend out to a range of 30 m, will you hit the object before coming to a stop?

b) How long will it take to stop?

Answer 1

a) To determine if the car will hit the object before coming to a stop, we need to calculate the distance required to stop the car, assuming maximum braking deceleration. We can use the following formula:

d = (v^2) / (2a)

where:

d = distance required to stop

v = initial velocity

a = acceleration/deceleration

In this case, v = 100 km/h = 27.78 m/s (converted from km/h to m/s)

a = -7 m/s^2 (negative sign indicates deceleration)

We know that the car's headlights extend out to a range of 30 m, so if the distance required to stop the car is greater than 30 m, the car will hit the object before coming to a stop.

Plugging in the values to the formula, we get:

d = (27.78^2) / (2 x -7) = 108.61 m

Since 108.61 m is greater than 30 m, the car will hit the object before coming to a stop.

b) To calculate the time required to stop, we can use the following formula:

t = v / a

where:

t = time required to stop

v = initial velocity

a = acceleration/deceleration

Plugging in the values, we get:

t = 27.78 / 7 = 3.97 s

Therefore, it will take 3.97 seconds to stop the car.