Moving about (1 Viewer)

[letsdie45]

Hi,
can someone explain how to approach this question.

A 1000kg car is moving at 25m/s when a net force of 200N acts to slow the car. This force acts while the car moves through a distance of 300m. What is the new speed of the car?

thanks.

 

[untouchablecuz]

Hi,
can someone explain how to approach this question.

A 1000kg car is moving at 25m/s when a net force of 200N acts to slow the car. This force acts while the car moves through a distance of 300m. What is the new speed of the car?

thanks.

if the force acts to slow the car

F = 200 against the car

so in the direction of the cars movement

F = -200

but by newtons second law F=ma

so -200 = 1000a --> a = -(1/5) m/s^2

using v^2 = u^2 + 2ad

(velocity after 300m)^2 = 25^2 + 2(-1/5)(300) = 505

so, velocity after 300m = sqrt(505) = 22.47 m/s