4.1.3 The Work Done by a Variable Force Flashcards
The Work Done by a Variable Force
- In one dimension the work done by a variable force, Fx, is .
- In two dimensions the work done by a variable force, , is .
True or false?
Suppose equal amounts of work are done on objects A and B. Therefore, the displacements of both objects are equal.
false
Suppose a force Fx = (1/3)x acts on an object. Assume at x=0 the force pushes the object and it starts moving to the right. What happens to the magnitude of the work done as the object moves to the right?
More work is done.
True or false?
Suppose a force equal to (1/2) x acts on an object, as shown in the figure. The work done on the object in moving it from 1 to 2 should equal the work done in moving it from 3 to 4 because in each case the displacement 2 − 1 = 4 − 3 = 1 is the same.
false
Given a force-displacement curve as shown in the figure, what does the area of the region enclosed by the curve represent?
The work done on the object by the force
For a variable force acting on an object from Position 1 to Position 2, the work done can be approximated by W = sigma Fx delta x. How can the approximation be improved.
By making delta x smaller
The most general definition of work done by a force on an object constrained to move along one dimension is given by which of the following formulas?
W = F delta x cos theta
What is the integral of the function x ^4 in the interval from c to d ?
x^5/5 | = 1/5(d^5-c^5)
Suppose a force F = 3x^2 N is acting on an object that undergoes a displacement from x = 1m to x = 2m. What is the work done on the object?
7 J
Suppose the force acting on an object depends on its position as shown in the figure. To calculate the work done by this force, which of the following techniques can be employed?
Slice the displacement and calculate delta W = f(delta x)
