1. Exam 1: Chapters 1-4
60% Problems – one problem from WebAssign with different numbers
Understand homework problems
Review notes and text
Try new problems
40% Multiple Choice Questions
Review Power Points (on web page)
Review Before Class Assignments
Try Questions
Graphs, Pictures and Drawings (Sketches)
Don’t rely on memorized equations

2. Chapter 5 The Laws of Motion
5-1a Force – a push or pull.
CT1: The force of the elevator on Norbert and Zot is
up.
down.

3. Assume the elevator is near the Earth’s surface and that it is right-side up in the cartoon.
CT2: The force of the non-sticky elevator surface on Norbert and Zot is
up.
down.

4. Assume the elevator is near the Earth’s surface and that it is right-side up in the cartoon.
CT3: The acceleration of Norbert and Zot is
up.
down.
zero

5. Figure 5. 1 Some examples of applied forces
Figure 5.1  Some examples of applied forces. In each case a force is exerted on the object within the boxed area. Some agent in the environment external to the boxed area exerts a force on the object. NOTE: Old incorrect kick image underneath – a click reveals it.
Fig. 5.1, p.113

6. 5-1 B. Mass
The mass of an object is the amount of matter (stuff) in that object. It is the same for a given object everywhere in the Universe. Mass is also called inertia because it resists being moved.

7. 5-2 Newton’s First Law: A body remains in uniform motion (or at rest) unless acted upon by a net external force.
acceleration due to Earth’s rotation  0.03 m/s2
acceleration due to Earth’s orbit  m/s2
acceleration due to Sun’s orbit  2 x m/s2
An inertia frame of reference is a coordinate system (or frame) in which Newton’s Law’s hold.
We will assume that the Earth’s surface is an inertial frame and not make errors greater than 0.03/10 = 0.3%.

8. CT4 A. B. C. D. E.

9. A. B. C. D. E.
CT5

10. 5-3 Newton’s Second Law: The net external force is equal to the mass times the acceleration.
F = ma
Force and acceleration are vectors
Fx = max
Fy = may remember Galileo!
Fz = maz
Normally we will do problems in a plane with only x and y components.

11. Calibrating a “Force Meter”
Experiments show forces add as vectors.

12. Acceleration is Proportional to Force

13. Acceleration is Inversely Proportional to Mass

14. Applications of Newton’s Laws - Method
Draw picture of the problem.
Choose body (bodies) to isolate.
Draw Free Body Diagrams (FBDs) for isolated bodies.
Choose and label coordinate axes.
Apply Newton’s 2nd Law: Fx = max and Fy = may
Solve for F, m or a.
Work out kinematics.
Check solution is reasonable.
P5.6 (p.136)

15. Concept Question 6
P5.6b: If the parachutist comes to rest over a shorter distance, the force exerted by the ground will be
greater.
less.
the same.

16. FAB and FBA are 3rd Law pairs.
5-4 Newton’s Third Law: If body A acts on body B, then body B acts back on body A with a force equal in magnitude but opposite in direction. A B
FAB
FBA
FAB and FBA are 3rd Law pairs.

17. A. C. B. D. E.
CT7

20. Concept Question 8
P5.18b: If the 5 N force is applied to the heavy box instead, the contact force between the boxes will be
greater.
less.
the same.
P5.18
(p.137)

21. 5-5 The Vector Nature of Forces
Two Astronauts Pushing a Satellite with Forces that Differ in Magnitude and Direction

22. P5.22 (p.137)

23. P5.28 (p.138)

24. Orbit of Moon about the Sun
Exaggerated and incorrect
Actual

25. 5-6 Gravitational Force or Weight Fg = mg (weight) g = -9.81 j (m/s2 )x y
Apparent Weight is the force you actually feel pushing on you – often the floor.

26. P5.35 (p.138)

27. Concept Question 9
P5.35b: If the constant speed of descent is greater than 1.1 m/s, the force of air resistance is
greater.
less.
the same.

28. Concept Question 10
P5.33a: Your normal weight is 610 N and the scale in the elevator reads 720 N. The acceleration of the elevator
upward.
downward.
zero.

29. Concept Question 11
P5.33c: Your normal weight is 610 N and the scale in the elevator reads 720 N. The magnitude of the velocity of the elevator is
increasing.
decreasing.
zero.
impossible to determine without more information.

30. 5-7 Normal Forces The Normal Force May Equal the Weight

31. The Normal Force May Differ from the Weight

32. An Object on an Inclined Surface
P5.42 (p.138)

33. Concept Question 12
P5.42b: If the angle of the incline is decreased, the normal force will
increase.
decrease.
stay the same.

34. CT13 A. B.