Well i think the answer is impossible to find because there is no picture
Answer:
The forces that do non-zero work on the block are gravity and normal reaction force
Explanation:
The formula for accelerational displacement is at^2/2, so we know that 3.9t^2/2 = 200, or 3.9t^2 = 400. t =

, at = v, so
Answer:
v = 72 km / h
Explanation:
The definition of average speed is the distance traveled between the time interval
v = Δx / Δt
let's find the distance traveled
x = 60 + 30
x = 90 km
time spent, all time must be included, travel time and when stopped
t = 0.45 + 0.15 + 0.5+ 0.15
t = 1.25 h
we substitute in the initial equation
v = 90 / 1.25
v = 72 km / h
in going from one city to the other
1 - Vibrate east and west
Sound waves are <em>longitudinal waves</em>, that means the vibrations are parallel to the direction of energy transfer. If the energy transfer is going East, then the vibrations will be East and West creating compressions and rarefactions in the air.