Un camión viene disminuyendo su velocidad en forma uniforme de 100 km/hr. Si para esto tuvo que frenar 1500 m. Calcular ¿Que desaceleración produjeron los frenos?

A truck has been slowing down uniformly at 100 km / hr. If for this you had to stop 1500 m. Calculate What deceleration caused the brakes?

Explanation:

The truck is initially moving at 100km/hr

Then, the initial speed is

u = 100km/hr = 100×1000/3600

u = 27.778m/s

The truck travel a distance of 1500m before coming to rest.

Therefore, since the truck comes to rest, the final velocity is 0m/s

v = 0m/s

And the distance is

S= 1500m

Calculate deceleration a?

Using equation of motion

v² = u² + 2as

0² = 27.778² + 2 × a × 1500

0 = 771.6 + 3000a

-3000a = 771.6

a = 771.6/-3000

a = —0.257 m/s²

The negative sign is show that the car is decelerating, therefore, the deceleration is 0.257m/s²

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west