lec10

lec10 Calendar
Lecture 09: Statics Applications and Elasticity

PHYS 1750: SELECTED TOPICS in PHYSICS
LECTURE 10. Work and Energy.

6.i. Concept of Energy

6.1. Work as a Form of Energy

1. Concept of path of motion

2. Work when force is constant

a. W = F ^. d = Fdcosq : note W is a scalar
Fcosq is the component of force parallel to the path

b. Units: Newton*meters = Joules

c. Don't confuse with torque, which has the same units

6.2. Kinetic Energy

1. Definition: E_k=mv²/2; also Joules

2. Work-K.Energy theorem: change in K.E. = work.

3. Derivation in cases of parallel, constant force:
W=Fd=mad, use 2ad=v²-v_o², then W=mv²/2 - mv_o²/2

6.3. Gravitational Potential Energy

1. What happens when work is done against gravity?

2. Definition: E_p=mgh

6.4. Spring Potential Energy

1. What happens when work is done against a spring?

2. Hooke's Law: F = kx

a. x = displacement from equilibrium

b. k = spring constant

3. Force not constant: use average force: E_p=W=Fd=(kx/2)x=kx²/2

Review Questions follow next lecture.
Lecture 11: Conservation of Energy

6.i.	Concept of Energy
6.1.	Work as a Form of Energy
	1.	Concept of path of motion
	2.	Work when force is constant
		a.	W = F ^. d = Fdcosq : note W is a scalar Fcosq is the component of force parallel to the path
		b.	Units: Newtonmeters = Joules*
		c.	Don't confuse with torque, which has the same units
6.2.	Kinetic Energy
	1.	Definition: E_k=mv²/2; also Joules
	2.	Work-K.Energy theorem: change in K.E. = work.
	3.	Derivation in cases of parallel, constant force: W=Fd=mad, use 2ad=v²-v_o², then W=mv²/2 - mv_o²/2
6.3.	Gravitational Potential Energy
	1.	What happens when work is done against gravity?
	2.	Definition: E_p=mgh
6.4.	Spring Potential Energy
	1.	What happens when work is done against a spring?
	2.	Hooke's Law: F = kx
		a.	x = displacement from equilibrium
		b.	k = spring constant
	3.	Force not constant: use average force: E_p=W=Fd=(kx/2)x=kx²/2