Ann is driving down a street at 58 km/h.
Suddenly a child runs into the street.
If it takes Ann 0.778 s to react and apply
the brakes, how far will she have moved before
she begins to slow down?
V = 58km/h = 58,000m/3600s = 16.1 m/s.
d = 16.1m/s * 0.778s = 12.53 m.
To find out how far Ann will have moved before she begins to slow down, we need to calculate the distance she travels during the reaction time.
First, we need to convert Ann's speed from km/h to m/s as the unit of time used here is in seconds. To do that, we can use the conversion factor: 1 km/h = 0.27778 m/s.
So, Ann's speed in m/s would be:
Speed = 58 km/h × 0.27778 m/s = 16.11 m/s (rounded to two decimal places.)
Next, we can calculate the distance traveled during the reaction time by using the formula: Distance = Speed × Time.
Given that the reaction time is 0.778 s, we can plug in the values:
Distance = 16.11 m/s × 0.778 s = 12.54 meters (rounded to two decimal places.)
Therefore, Ann will have moved approximately 12.54 meters before she begins to slow down.
To find out how far Ann will have moved before she begins to slow down, we need to calculate the distance traveled during the reaction time.
The formula to calculate distance is:
Distance = Speed × Time
Given that Ann's speed is 58 km/h and the reaction time is 0.778 s, we need to convert the speed to meters per second (m/s) and the time to seconds.
To convert the speed:
1 km = 1000 m
1 hour = 3600 s
So, the speed in m/s is:
58 km/h × (1000 m/1 km) × (1/3600 h/1 s) = 16.1 m/s
Next, we can plug the values into the distance formula:
Distance = Speed × Time
Distance = 16.1 m/s × 0.778 s
Distance ≈ 12.53 meters
Therefore, Ann will have moved approximately 12.53 meters before she begins to slow down.