**Unit 11: Work, Energy and
Power**

**Problem Set F**

**Overview:**

Problem Set F consists of six difficult (mostly) and complex problems which test your ability to use the work-energy equation to analyze a physical situation. Like Sets C, D and E, the main equation of importance is

Each term of this equation can be calculated from their respective equations and the stated values of mass (m), speed (v), height (h), spring constant (k), spring compression/stretch distance (x), force (F) and displacement (d).

KE =
0.5•m•v^{2} |
PE_{grav} =
m•g•h |
PE_{spring} =
0.5•k •x^{2} |
W_{nc} =
F•d•cos() |

In some instances, the force will be a friction force and will
have to be calculated from the coefficient of friction and the normal
force (F_{frict} = mu•F_{norm}). In other
instances, the friction will be present on an inclined plane and the
normal force will have to be determined by first calculating the
perpendicular component of gravity (F_{perp} =
m•g•cos()).
In more complicated cases, there will be more than one
non-conservative work term. In instances in which an object moves
along an inclined plane and then along a horizontal surface, the
force of friction is different on the two surfaces; thus a work term
for the incline and for the horizontal surface will have to be
written separately.

Each problem of the set includes its own unique complications. In one problem, a projectile trajectory is analyzed using energy (rather than the usual kinematics); the horizontal speed at the peak position will have to be equated with the horizontal component of the initial launch velocity. In another problem, trigonometry will have to be used to determine the initial height of a pendulum-like object using the angle of deflection with respect to the vertical. Two problems involve springs, demanding the use of the elastic potential energy equation (above). One problem involves a force exerted downward at an angle in order to accelerate an object across a horizontal surface.

**Additional Readings/Study
Aids:**

The following pages from The Physics Classroom tutorial may serve to be useful in assisting you in the understanding of the concepts and mathematics associated with these problems.

Situations Involving External Forces | Situations Involving Energy Conservation

Resolving Fgrav on an Inclined Plane

View Sample Problem Set.

Return to: Set F Overview Page || Audio Help Home Page || Set F Sample Problems

Audio Help for Problem: 1 || 2 || 3 || 4 || 5 || 6 ||

Retrieve info about: Problem-Solving || Audio Help || Technical Requirements || CD-ROM

Return to: ChemPhys Problem Set Page || CP 173 Home || CP 273 Home || The Physics Classroom