A car doing 126 km/h brakes steadily and comes to rest in 200 m. How long does it take to stop, in seconds?

expects 11.4 s

24 checks, 0 agreed

draft 24: failed while solving — RuntimeError: no equation determines the time taken of braking from what is known the engine knows: known: velocity of car at start of braking from ground; displacement of car during braking; velocity of car at end of braking from ground; displacement_a_time(braking): average velocity of car during braking == (displacement of car during braking / time taken of braking) — not yet known: average velocity of car during braking; path_a_time(braking): average speed of car during braking == (path length of car during braking / time taken of braking) — not yet known: average speed of car during braking; path length of car during braking; velocity_gained_a_time(braking): average acceleration of car during braking == (change of velocity of car during braking / time taken of braking) — not yet known: average acceleration of car during braking; change of velocity of car during braking; velocity_after_a_time(braking): velocity of car at end of braking from ground == (velocity of car at start of braking from ground + (acceleration of car during braking * time taken of braking)) — not yet known: acceleration of car during braking; position_after_a_time(braking): position of car at end of braking == ((position of car at start of braking + (velocity of car at start of braking from ground * time taken of braking)) + ((acceleration of car during braking * (time taken of braking ** 2)) / 2)) — not yet known: position of car at end of braking; position of car at start of braking; acceleration of car during braking; mean_of_the_velocities(braking): (position of car at end of braking - position of car at start of braking) == (((velocity of car at end of braking from ground + velocity of car at start of braking from ground) * time taken of braking) / 2) — not yet known: position of car at end of braking; position of car at start of braking

solution.rb · draft 24 failed while solving

1solve :car_braking_to_rest, using: UniformAcceleration do2  objects :car3  car.goes(:braking)45  take initial_speed: car.initial_velocity, distance: car.displacement(during: braking).magnitude678  deduce_from "comes to rest", car.final_velocity => "0 m/s"910  time = braking.time_taken11  answer time:, in: "s", figures: 31213  conclusion "The car slows down at a steady rate, so the time to stop is the distance divided by the average speed."14end

RuntimeError: no equation determines the time taken of braking from what is known the engine knows: known: velocity of car at start of braking from ground; displacement of car during braking; velocity of car at end of braking from ground; displacement_a_time(braking): average velocity of car during braking == (displacement of car during braking / time taken of braking) — not yet known: average velocity of car during braking; path_a_time(braking): average speed of car during braking == (path length of car during braking / time taken of braking) — not yet known: average speed of car during braking; path length of car during braking; velocity_gained_a_time(braking): average acceleration of car during braking == (change of velocity of car during braking / time taken of braking) — not yet known: average acceleration of car during braking; change of velocity of car during braking; velocity_after_a_time(braking): velocity of car at end of braking from ground == (velocity of car at start of braking from ground + (acceleration of car during braking * time taken of braking)) — not yet known: acceleration of car during braking; position_after_a_time(braking): position of car at end of braking == ((position of car at start of braking + (velocity of car at start of braking from ground * time taken of braking)) + ((acceleration of car during braking * (time taken of braking ** 2)) / 2)) — not yet known: position of car at end of braking; position of car at start of braking; acceleration of car during braking; mean_of_the_velocities(braking): (position of car at end of braking - position of car at start of braking) == (((velocity of car at end of braking from ground + velocity of car at start of braking from ground) * time taken of braking) / 2) — not yet known: position of car at end of braking; position of car at start of braking