chapter 5 physics a first course energy and systems

Chapter 5Physics A First Course Energy and Systems

Energy and SystemsForces in Equilibrium

5.1 The Force Vector

5.2 Forces and Equilibrium

5.3 Friction

5.4 Torque and Rotational Equilibrium

5A Investigation: Equilibrium and Forces

Key Question:

What can we say about forces when nothing is moving?

*Students read text section 5.1

AFTER Investigation 5A

5A Investigation Topics

Use spring scales.

Make an object in equilibrium.

Measure forces on an object that is in equilibrium.

Draw free-body diagrams.

Measure the force of gravity.

Distinguish between weight and mass.

Chapter 5.1 Objectives and Vocabulary

scalar magnitude vector component free-body diagram

Draw vectors to scale to represent a quantity's magnitude and direction.

Solve vector problems.

Find a vector's components.

5.1 Pythagorean Theory

a2 + b2 = c2

side b

hypotenuse, side c

side a

Chapter 5.2 Objectives and Vocabulary equilibrium

normal force resultant Hooke's lab spring constant

Explain what it means to say an object is in equilibrium.

Use free-body diagrams to find unknown forces.

Explain how springs exert forces.

Add force vectors.

5B Investigation: Friction

Key Question:

How do we account for friction?

*Students read text section 5.3

AFTER Investigation 5B

5B Investigation Topics

Measure kinetic energy of a system. Determine the force of friction from experimental

data. Compare friction in a car to friction in a sled. Use Newton's second law to calculate force of

friction in a rolling car. Compare the strength of sliding friction to that of

rolling friction. Determine how the force of friction varies with

speed.

Chapter 5.3 Objectives and Vocabulary friction

sliding friction static friction lubricant

Distinguish between sliding and static friction.

Explain the cause of friction.

Discuss reasons to increase or decrease friction.

Chapter 5.4 Objectives and Vocabulary torque

rotate axis of rotation line of action lever arm rotational

equilibrium

Explain how torque is created.

Calculate the torque on an object.

Define rotational equilibrium.