In class principle summary

Orbits are extended projectile motion

Only force acting on orbiting object is gravity, thus in

free Fall motion

Orbital speed and period is

Note g can change

For this chapter stay close to earth and

g = 9.8

8.3: Circular Orbits

8.4: Fictitious Forces

Really just

Newton’s 1st law

application

Happen because not in

inertial reference frame

Examples of water in bucket and roller coasters

Effect on gravity

g=9.83 - inertial effect (.033) = g = 9.80

Small enough we will

neglect rotational effects

Kinematic equations

of motion in rotational reference frame

Dynamics

in Nonuniform Circular Motion

Find total Force/acceleration using Pythagorean theorem

8.5: Nonuniform Circular Motion

Questions?

Quiz

Orbital velocity depends upon:

1. Mass of satellite 2. Mass of planet

3. Acceleration due to gravity

4. Radius 5. Rotation of planet

A. 1,3,5

B. 1,2,3,4

C. 2,3,4

D. 1,2,4,5

E. 3,4

F. 1,2,5

Water stays in a bucket as you swing it around your head because:

A. It is an application of Newton's 3rd law

B. The centrifugal force acts on it

C. Its inertia is keeps it there

D. The bottom of the bucket pulls it up

E. Vanderwall attraction

F. It is frozen and stuck in bucket

Non uniform circular motion problems are:

A. Solvable using circular kinematic equations

B. Can't be solved unless transformed into linear terms

C. Are just simply too hard to solve, give up.

#60 Father stands on conical 20 degree hill and spins his 20 kg child on a 5.0 kg cart, with 2 meter rope. Friction is negligible and speed is 14 rpm, what is tension

Example

20

0

20

20

0

0

G

N

**F**

**F**

**T**

20

0

2 m

radius = r = 2 cos(20) = 1.88

**Two wires are tied to the 2.0 kg sphere shown in the figure. The sphere revolves in a horizontal circle at constant speed.**

**For what speed is the tension the same, and what is that speed?**

**2.9 m/s**

14 N

14 N

**A 500 g steel block rotates on a steel table while attached to a 1.20 m -long hollow tube. Compressed air fed through the tube and ejected from a nozzle on the back of the block exerts a thrust force of 4.81 N perpendicular to the tube. The maximum tension the tube can withstand without breaking is 60.0 N . Assume the coefficient of kinetic friction between steel block and steel table is 0.60.**

**2.55**