Question

17. A train is travelling at a speed of 90 km/h.

Brakes are applied, so as to produce a
uniform acceleration of -0.5 m/s2. Find how
far the train will go before it is brought to rest?
Pg 110​

Answer 1

x = 625 m

Step-by-step explanation:

To solve this exercise we use the kinematics relations

v² = v₀² - 2 a x

indicate that the train stops therefore its final speed is zero (v = 0)

0 = v₀² - 2a x

x =
`(v_o^2)/(2a)`

let's slow down to the SI system

v₀ = 90 km / h (1000 m / 1km) (1h / 3600 s) = 25 m / s

let's calculate

x =
`(25^2)/(2 \ 0.5)`

x = 625 m