To find the acceleration of the car, we can use the formula for acceleration, which is
a = (v_f – v_i) / t
where:
- a is the acceleration
- v_f is the final velocity
- v_i is the initial velocity
- t is the time taken
In this case:
- The initial velocity (v_i) is 20 miles per hour.
- The final velocity (v_f) is 10 miles per hour.
- The time (t) is 5 seconds.
Before we can calculate acceleration, we need to convert the speeds from miles per hour to a more manageable unit for our calculation. We can convert miles per hour to feet per second, knowing that 1 mile = 5280 feet and 1 hour = 3600 seconds:
20 mph = (20 × 5280) / 3600 ≈ 29.33 feet per second
10 mph = (10 × 5280) / 3600 ≈ 14.67 feet per second
Now we can substitute these values into our acceleration formula:
a = (14.67 – 29.33) / 5
a = -14.66 / 5
a ≈ -2.93 feet per second squared
This negative sign indicates that the car is decelerating. Therefore, the acceleration of the car as it slows down from 20 miles per hour to 10 miles per hour in 5 seconds is approximately -2.93 feet per second squared.