Example: How much is the kinetic, potential, and total mechanical energy of a car (m=1200 kg) moving at 20 m/s at p. A?
Question: How much is the total energy at B in the absence of any dissipative forces?
Question: How much is the speed of the car at p.B in the absence of any dissipative forces?
Question: How much is the total energy at B if friction removed 10,000 J from the car as it moved from p. A to p.B?
📚 Review of Vector Dot Product
Constant Force applied to an object with displacement d
Example: A 1,470-N force pushes a 500-kg piano up a 10-m long ramp as shown on the diagram. What is the work done by (a) Gravity; (b) the pushing force; and (c) the normal force.
Question. What is the acceleration of the piano?
1-Dimensional Variable Force applied to an object with displacement x
Example: A 1-dimensional force acts on an object. Calculate its work as the object moves from 0 to 2.0 m
1-Dimensional Graphical Representation of the Work: F vs. x diagram
Example: What is the work of the force F from x=1 to x=3 m?
3-Dimensional Variable Force applied to an object with displacement
Example: A force N is applied on an object as it moves from position (1,0,0) m to position (1,-4, 8) m. Determine the work done by the force.
1 horsepower = 745.7 W (Power)
1 KW.h = 3.6 MJ (Energy)
A constant force with magnitude 20 N is applied to a toy-wagon by a child. If the force makes an angle with the ground equal to 30°, and the child drags his wagon for 5 m, (a) calculate the work done by the child, (b) the gravitational force, (c) the normal force.
Question. Consider the toy-wagon sliding along the surface. If its mass is 2.00 kg and the coefficient of kinetic friction is 0.6, what is the work done by the friction?