Question

The driver of a 600.0 kg sports car, heading directly for a railroad crossing, 300.0 m away, applies the brakes in a panic stop. The car is moving at 40.0 m/s and the brakes can supply a force of 1500 N. a.) How fast will the car be moving when it reaches the crossing? b.) Will the driver escape collision with a freight which, at the instant the brakes are applied, is still blocking the road and still requires 11.0 s to clear the crossing?

Answer 1

Answer:

a)  V =10 ms⁻¹

b) yes

Explanation:

there is a net force acting on the care while braking , this will make the car decelerate . We can find the amount of deceleration by applying newton's second law of motion here

Force = mass * acceleration

-1500 = 600 *a

a = -2.5 ms⁻² ---------(1)

applying motion equations for the movement

where V - Velocity @ crossing

          U - initial velocity

          s - distance

          t - time taken

V² = U² + 2as

    = 40² +_2*(-2.5)*300

 V =10 ms⁻¹

V = U + a t

10 = 40 -2.5*t

t = 12 s

car still needs 12 seconds to reach the crossing point.As the freight can clear within 11 seconds , by the time the car is reaching the crossing , it wont meet the freight to collide