Term
| Uniform Circulation Motion def |
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Definition
| motion in a circle of a constant radius at a constant speed |
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Term
| In uniform circular motion, instaneous velocity is always ____ to the circle |
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Definition
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Term
| give the formula for the acclertaion in uniform circular motion |
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Definition
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Term
| For an object to be in uniform circulation there must be ______ |
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Definition
a net force acting on it
ex. like swinging a ball on a string |
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Term
| The accleration in uniform circular motion is called____ or ____ accleration and it points__________ of the circle |
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Definition
centripetal or radial accleration,
towards center |
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Term
| If the centrigufal force vanishes the object will fly ____ to the circle instead of _____ |
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Definition
off tangent, outward
the natural tendency of the object to move in a circle must be overcome |
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Term
| express the acceleration in uniform circualr motion in terms of force |
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Definition
ΣFR= maR= m v2
r
recall that sum of net force= accleration x mass |
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Term
Describe how a car travels along a curve, what forces are acting?
If the roads is flat? |
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Definition
there must be a net force towards the center of the actual curve (which is arc shaped ∩)
b. If the road is flat the force is friction |
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Term
Highway Curves, Banked & Unbanked:
If the frictional force is insufficent the car will tend to move in a ____ |
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Definition
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Term
The Clothoid Loop
The radius at the bottom is significantly (smaller/bigger) than the radius at the top of the clothoid loop |
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Definition
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Term
Highway Curves, Banked, and Unbanked
___________ the curve can help cars from skidding |
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Definition
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Term
Describe how banked highway curves works. |
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Definition
There is ONE speed in which the :
entire centripetal force is supplied by the HORIZONTAL (x)component of the NORMAL force
NO friction is required!
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Term
Give the formulas that make banking of highway curves possible.
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Definition
(x) FN cos Ө = mg
(y) FN sin Ө =mac = (mg ) sin Ө
(cosӨ)
= (m’s will cancel)
= (g/cosӨ) sin Ө = v2 /r
(recall sin/cos = tan)
= g tan Ө = v2 /r
Final Equation:
V=√gr tan Ө
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Term
Newton's Law of Universal Gravitation
If the force of gravity is being excerted on objects on Earth, what is the origin of the force? |
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Definition
| this force comes from the Earth, this force also keeps the Moon in its orbit. |
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Term
| What 2 factors influence the gravitional force & why? |
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Definition
- the gravitional force is proportional to both masses involved
(aka the Earth excerts a downward force on you & you excert an upward force on Earth b/c these masses are very opposite the rxn is small & negliable , however the rxn force btwn the Earth & moon is SIGNIFICANT)
- the gravitional force decreases as the distance btwn the two masses increases (distance is measured from the center of both of the masses being considered)
- (which can be represented by radius squared)
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Term
| Write the formula for Law of Universal Gravitation |
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Definition
F= G m1m2
r2
where G=6.67 x 10-11 N•m/kg2
r= distance btwn objects
m1= object/planet staying still
m2= one that is moving |
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Term
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Definition
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Term
Satellites & Weightlessness
How do satellites work? |
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Definition
the tangential speed:
- must be HIGH enough so that satellite does not return to Earth
- but not too high that it escapes Earth's gravitional pull
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Term
| The satellite is kept in orbit by its ____ |
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Definition
| speed, it is continually falling, but the Earth curvees from Earth underneath it. |
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Term
| T or F: Objects in orbit do not have a gravitional force acting on them. |
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Definition
False, alhough objects in orbit are said to experience a gravitational force,there is still a gravitional force.
- The satellite & all of its components are in FREE FALL= no normal force
- (thats where the feeling of weightlessness comes from)
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Term
| What is apparent weightlessness |
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Definition
- Just like the:
- satellite & all of its components are in FREE FALL= no normal force
- (thats where the feeling of weightlessness comes from)
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Term
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Definition
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Term
Keplers First Law:
The orbit of each is |
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Definition
| an ellipse, with the sun at one focus |
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Term
Kepler's 2nd Law:
an imaginary line____... |
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Definition
| drawn from each planet to the Sun sweeps out equal areas in equal times. |
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Term
| Kepler's 3rd Law: relate the orbit & orbital law |
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Definition
the period2 of the orbit for all objects orbiting the same planet/star
depends on
orbital distance3
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Term
Give formula for Kepler's 3rd law
that relates M, r,G, T2 |
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Definition
(4∏2/GM)• r3 = T2
where T2 = the period squared for all objects orbiting the same planet/star
G= 6.67 x 10-11
r3 = orbital distance cubed
M= mass of planet staying still
*note :memorze this formula b/c it can switched around to solve for other variables for example if you want to find the mass of a planet knowing how far it is from Earth
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Term
The greater the speed v, then ____
&
The greater the radius then______ |
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Definition
the higher the speed:
the FASTER the velocity changes direction
the higher the radius:
the LESS rapidly the velocity changes direction |
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Term
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Definition
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Term
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Definition
| # of revolutions per second |
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Term
| period is represented by what letter? |
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Definition
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Term
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Definition
| time required for 1 complete revolution |
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Term
| Give the equation that relates period + frequency |
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Definition
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Term
| Give the equation for an object revolving in a circle (of circumference 2πr), at a constant speed v |
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Definition
v= 2πr
T
This is true because when an object travels 1 circumference it also traveled one revolution. |
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Term
newtons gravitational force formula:
F=G m1m2/r2
unit for distance |
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Definition
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Term
newtons gravitational force formula:
F=G m1m2/r2
unit for mass |
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Definition
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Term
newtons gravitational force formula:
F=G m1m2/r2
unit for answer |
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Definition
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Term
Give formula for Kepler's 3rd law
that relates the period (T) and the orbital radius (r) for two planets |
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Definition
(T1/T2 )2 = (r1 / r2 )3
* use this formula when you want to determine the distance of planet (r) from anothe planet, knowing its period (T). |
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Definition
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