Assuming you're working in a 3D cartesian coordinate system, i.e. each point in space has an x, y, and z coordinate, you add up the forces' x/y/z components to find the resultant force.
Mary walks:
d 1 = 80 m, d 2 = 125 m, d 3 = 45 m
t = 10 minutes = 600 seconds;
Average speed:
v = ( d 1 + d 2 + d 3 ) / t
v = ( 80 m + 125 m + 45 m ) / 600 s
v = 250 m / 600 s
v = 0.4167 m/s ≈ 0.42 m/s
Answer:
E ) 0.42 meters/second
Average Acceleration = (change in speed) / (time for the change)
Change in speed = (ending speed) - (starting speed)
= 15 m/s - 24 m/s = -9 m/s
Acceleration = (-9 m/s) / (12 sec) = - 0.75 m/s² .
Because the position depends on the amount of time that has passed.
