Physics Car Question

Question

A car slows to a stop in 5 seconds. If it was going 80km/hr

A) Find the acceleration

B) Find the stopping distance

Answer 1

Hi Isaiah R.,

Acceleration is the change in velocity over the change in time, Δv/Δt.

Lets first convert 80 km/hr to __m/s.

80 km/hr*(1 hr/3600 s)*(1000 m/1 km) = 22.22...m/s

We can use this to find the acceleration:

a) Δv/Δt = (v_f - v_i)/(t_f - t_i) = (0 - 22.22 m/s)/(5 s- 0) = -4.44 m/s² , (negative acceleration or deceleration)

To find the stopping distance we can use x = x_o + v_ot + (1/2)at², with x_o = 0, v_o = 22.22 m/s and a = -4.44 m/s²:

(b) x = v_ot + (1/2)at² = 22.22*(5) + .5*(-4.44)*5² = 55.56 m

I hope this helped, Joe.