Ahorse began running due east and covered 25 km in 4.0 hr. what is the average velocity of the horse?
a) 0.16 km/hr due east
b) 6.25 km/hr due east
c) 16 km/hr due east
d) 100 km/hr due east

B) due east

Explanation:

Conceptual analysis

The average speed (v) is defined as the relationship between the displacement (d)  that a body made and the total time (t) it took to perform it and is calculated by the following formula:

Formula (1)

v: velocity in m/s

d: Displacement (m)

t: Time (s)

Known data

We know the following data

d = 25 km

t = 4.0 hr

Problem development

We replace data in formula (1):

potential energy is directly proportional to height.

more height = more potential energy.

greatest increase in height = greatest increase in potential energy

where are the points with the greatest increase in height ?

has to be c-e or d-e .

we need to know the time interval during which the force acts. impulse of force = momentum change