Question

The net force on the propeller of a 3.2 kg model airplane is 7.0N forward. What is the acceleration of the airplane? If it starts from rest, what is the velocity of the plane after 2.5 seconds?

Answer 1

Answers:

Acceleration = 2.1875 m/s^2

Velocity after 2.5 seconds = 5.46875 m/s

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Work Shown:

Part 1

The mass is m = 3.2 and the force is F = 7.0

Apply the formula F = ma to find the acceleration to be...

F = ma

7.0 = 3.2*a

7.0/3.2 = a

2.1875 = a

a = 2.1875

The acceleration is 2.1875 m/s^2

Every second, the velocity of the plane is increasing by 2.1875 m/s.

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Part 2

We have the following variables

• vi = initial velocity = 0 m/s (since it starts from rest)
• vf = unknown final velocity (what we're trying to figure out)
• t = change in time = 2.5 seconds
• a = acceleration = 2.1875 m/s^2

Using one of the kinematics equations, we can then say,

vf = vi + a*t

vf = 0 + 2.1875*2.5

vf = 5.46875

After 2.5 seconds, the airplane is traveling 5.46875 m/s.

5.46875 m/s converts to roughly 12.2332 mph.