Question

part a: forced choice questions

1. which of the following statements are true about work? include all that apply

a. work is a form of energy
b. a watt is the standard metric unit of work.
c. units of work would be equivalent to a newton times a meter.
d. a kg·m²/s² would be a unit of work.
e. work is a time - based quantity; it is dependent upon how fast a force displaces an object.
f. superman applies a force on a truck to prevent it from moving down a hill. this is an example of work being done.
g. an upward force is applied to a bucket as it is carried 20 m across the yard. this is an example of work being done.
h. a force is applied by a chain to a roller coaster car to carry it up the hill of the first drop of the shockwave ride. this is an example of work being done.
i. the force of friction acts upon a softball player as she makes a headfirst dive into third base. this is an example of work being done.
j. an eraser is tied to a string; a person holds the string and applies a tension force as the eraser is moved in a circle at constant speed. this is an example of work being done.
k. a force acts upon an object to push the object along a surface at constant speed. by itself, this force must not be doing any work upon the object.
include all that apply

Explanation:

Work is defined as energy transferred by force over distance ($W = Fd\cos\theta$). Check each statement:

• A: True (work transfers energy, so it’s a form of energy).
• B: False (Watt is power unit; work unit is Joule).
• C: True (Newton·meter = Joule, work unit).
• D: True ($kg·m²/s² = Joule$, work unit).
• E: False (work depends on force/distance, not time; power depends on time).
• F: False (no displacement, so $W=0$).
• G: False (upward force perpendicular to horizontal displacement, $\cos90°=0$, $W=0$).
• H: True (force upward, displacement upward, work done).
• I: True (friction opposes motion, displacement occurs, work done).
• J: False (tension perpendicular to circular displacement, $\cos90°=0$, $W=0$).
• K: False (constant speed means net work is zero, but applied force does work equal to friction work).

Answer:

A. Work is a form of energy, C. Units of work would be equivalent to a Newton times a meter, D. A kg·m²/s² would be a unit of work, H. A force is applied by a chain to a roller coaster car to carry it up the hill of the first drop of the Shockwave ride. This is an example of work being done, I. The force of friction acts upon a softball player as she makes a headfirst dive into third base. This is an example of work being done.