Download Work Power Energy Exams1 (Work) and Problem Solutions 1. In the

Work Power Energy Exams1 (Work) and Problem Solutions
1.
In the picture given above F pulls a box having 4kg mass from point A to B. If the friction constant
between surface and box is 0.3; find the work done by F, work done by friction force and work done by
resultant force.
Work done by F;
Work done by friction force;
Work done by resultant force;
2. Applied force vs. position graph of an object is given below. Find the work done by the forces on the
object.
Area under the graph gives us work done by the force.
Work done between 0-5m:
Work done between 5-8m:
Work done between 8-11m:
Work done between 11-15m:
3. Different forces are applied to three objects having equal masses. Forces pull objects to height h. Find
the work done by the forces on objects and work done on gravity.
Since masses of the objects are equal, and distance taken by the objects are equal, work done on gravity of
three objects are equal.
4. In the picture given below, forces act on objects. Works done on objects during time t are W1, W2 and
W3. Find the relation of the works.
Horizontal components of the applied forces are equal to each other. Masses of the objects are also equal.
Thus, acceleration of the objects and distances taken are also equal.
Work done:
W=FX.X
W1=W2=W3
5. A box having 2 kg mass, under the effect of forces F1, F2 and F3, takes distance 5m. Which ones of the
forces do work.
Since box moves from point A to B, only F3 does work.
Work Power Energy Exam2 Problems and Solutions
Work Power Energy Exam2 and Problem Solutions
1. Applied force vs. position graph of an object is given below. Find the kinetic energy gained by the
object at distance 12m.
By using work and energy theorem we say that; area under the graph gives us work done by the force.
2. Box having mass 3kg thrown with an initial velocity 10 m/s on an inclined plane. If the box passes from
the point B with 4m/s velocity, find the work done by friction force.
We use conservation of energy theorem.
3. Three different forces are applied to a box in different intervals. Graph, given below, shows kinetic
energy gained by the box in three intervals. Find the relation between applied forces.
Slope of the EK vs. position graph gives applied force
4. A stationary object at t=0, has an acceleration vs. time graph given below. If object has kinetic energy E
at t=t, find the kinetic energy of the object at t=2t in terms of E.
Object has velocity at t=t;
V1=at
Object has velocity at t=2t;
5. An object does free fall. Picture given below shows this motion. Find the ratio of kinetic energy at
point C to total mechanical energy of the object.
Object lost 2mgh potential energy from point A to C.
According to conservation of energy theorem, this lost potential
energy converted to the kinetic energy. Thus; we can say that
kinetic energy of the object at point C is;