Now Playing: Lecture Notes for 4.6 to 4.9
Topic: Chap 4
4.6 Net Force
Net Force is the combination of all forces acting on an object.
4.7 Equilibrium
In Physics, Equilibrium is reached when the
Net Force = zero
Gravitational Force: the downward force of the book
Normal Force (also called Support Force): the upward "support" force exerted by the table on the book.
Tension is also a word for Force.
Question on page 52:
When you step on a bathroom scale, the downward force supplied by your feet and the upward force supplied by the floor compress a calibrated spring. The compression (this is also a word which means force) of the spring gives your weight. In effect, the scale measures the floor's support force.
What will each scale read if you stand on two scales with your weight divided equally between them?
What happens if you stand with more of your weight on one foot than the other?
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The resultant is the vector sum of two or more component vectors. See the example below:
The resultant of the forces applied by the pair of springs must equal 10 N if the 10 N bag of nails is in equilibrium.
4.8 Vector Addition of Forces
In non-vertically oriented spring scales, the tension is greater and depends on their angle from the vertical. The greater the angle, the greater the tension--see below:
4.9 The Moving Earth
The Earth is travelling 30 km/s as it orbits the Sun.
Why can the bird catch the worm by diving straight down at it? Does that conflict with the statement above?
