a motorist driving his car at a speed of 72km/hr observes that the traffic lights ahead of him turns red if he comes to a halt at the traffic light 5seconds starting from first find the distance of the car from the light when the motorist observed the red light
Vo = 72000m/3600s = 20 m/s.
V = Vo + a*t = 0.
20 + a*5 = 0, a = -4 m/s^2.
V^2 = Vo + 2a*d.
V = 0, Vo = 20 m/s, a = -4 m/s^2,
d = ?.
To find the distance of the car from the traffic light when the motorist observed the red light, we need to calculate the distance covered by the car in 5 seconds.
To do this, we first need to convert the speed from kilometers per hour (km/hr) to meters per second (m/s).
Given:
Speed of the car = 72 km/hr
Distance = ?
Time = 5 seconds
Converting speed from kilometers per hour to meters per second:
Speed in m/s = (Speed in km/hr) * (1000 m / 1 km) * (1 hr / 3600 s)
Speed in m/s = 72 * 1000 / 3600
Speed in m/s = 20 m/s (rounded to the nearest whole number)
Now, we can use the equation:
Distance = Speed * Time
Plugging in the values:
Distance = 20 m/s * 5 seconds
Distance = 100 meters
Therefore, the car is 100 meters away from the traffic light when the motorist observed the red light.