1. Vf^2 = Vo^2 + 2g*h.
Vf = 0.
Vo = 12 m/s.
g = -9.8 m/s^2.
h =
2. V = 90,000m/3600s = 25 m/s.
Vo = 126,000m/3600s = 35 m/s.
V = Vo + a*t.
a = (V-Vo)/t = (25-35)/t = -10/t.
V^2 = Vo^2 + 2a*d.
25^2 = 35^2 + 2(-10/t)*800.
625 = 1225 + (-16,000)/t.
-600 = -16000/t.
600t = 16000.
t = 26.7 s.
question 1 ..A 5 kg rock is thrown vertically upward at 12 m/s. How high did the rock rise?
question 2 The driver of a truck traveling at 126 km/h on a highway sees a sign which indicated that 800 m after the sign the maximum speed will be 90 km/h . When the truck passes the sign the driver steps on the brake until the truck slows to the new speed limit in the required distance. Assuming the acceleration is constant, how long does it take for the truck to decelerate?
1 answer
1 answer