Answer:
A) v_average = - 10 km / h, B) v = 1.6 m / s, v = 17.6 m / s
Explanation:
A) the average speed is the average speed of a body, if we assume that the direction of going up the hill is positive
v₁ = 40 km / h
v₂ = - 60 km / h
the average speed is
v_average =
v_average = ( 40 - 60)/2
v_average = - 10 km / h
B) in this case they indicate the acceleration a = 3.2 m / s² and the velocity vo = 9.6 m / s
i) the speed for 2.5 s above
v = v₀ + a t
as the time is earlier
t = - 2.5 s
we substitute
v = 9.6 - 3.2 2.5
v = 1.6 m / s
ii) the velocity for a subsequent time of 2.5 s
t = 2.5 s
we substitute
v = 9.6 + 3.2 2.5
v = 17.6 m / s