Final answer:
The cart's speed at point B is 21 ft/s.
Step-by-step explanation:
To find the speed of the cart at point B, we can use the equation
v = u + at
where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time taken.
Given that the cart takes 1.40 s to go from point B to point C and the final velocity at point C is 19.0 ft/s, we can rearrange the equation to solve for the acceleration:
a = (v - u) / t
Substituting the values, we get:
a = (19.0 ft/s - 14.0 ft/s) / 1.40 s = 5.0 ft/s²
Since the cart maintains a constant tangential acceleration, this acceleration is also the acceleration experienced from point A to point B.
To find the speed at point B, we can use the same equation with the given initial velocity of 14.0 ft/s and the acceleration of 5.0 ft/s²:
v = 14.0 ft/s + (5.0 ft/s²)(1.40 s)
Solving this equation gives:
v = 21 ft/s