CIRCULAR MOTION AND KEPLER'S LAWS

For an object attached to a string and rotated in a vertical circle,
its greatest speed will be
a. at the top of the circular path
b. at the side of the circular path
c. at the bottom of the circular path
d. anywhere on the circular path

c. at the bottom of the circular path

A car travels in a circle with constant speed. The net force
on the car
a. is zero because the car is not accelerating
b. is directed forward in the direction of travel
c. is directed toward the center of the circle
d. none of the above

c. is directed toward the center of the circle

If you whirl a tin can on the end of a string and the string suddenly breaks, the can will
a. spiral away from your hand
b. fly directly away from you
c. spiral in toward your hand
d. fly off, tangent to the circular path

d. fly off, tangent to the circular path

Calculate the velocity of an object moved around a circle with a radius of 1.65 m and an acceleration of 3.5 m/s2.
a) 2.4 m/s
c) 3.6 m/s
b) 3.9 m/s
d) 4.2 m/s

a) 2.4 m/s

Calculate the centripetal force required to make a 5 kg ball move 4 m/s in a circle with a radius of 2 m.
a) 10 N
c) 20 N
b) 30 N
d) 40 N

d) 40 N

Centripetal acceleration acts towards the ___________ of the circular motion
a) center
c) circumference
b) outside
d) radius

a) center

Bruno the bat flies at a speed of 0.5 m/s in circle of radius 1 m. What is his acceleration? ac = vt2/r = .52/1 = 0.25 m/s2 or ms-2
a) 0.25 ms-2
c) 0.5 ms-2
b) 1 ms-2
d) 2

a) 0.25 ms-2

What is the force that causes or provides centripetal acceleration when a car goes around a curve?
a) Friction
c) Gravity
b) Normal
d) Tension

a) Friction

The velocity is always _____ to the radius of a circle.
a) Outwards
c) towards the center
b) Tangent
d) faster

b) Tangent

You are moving a ball in a circle at a certain speed v. What would the speed be if you doubled the radius of the circle and keeping period constant.
a) 0.5 v
b) v
c) 2v
d) 4v

c) 2v

A test car moves at a constant speed around a circular track. If the car is 48.2 m from the track's center and has a centripetal acceleration of 8.05 m/s2, what is the car's tangential speed?
a) 19.7 m/s
c) 5.99 m/s
b) 0.17 m/s
d) 388.01 m/s

a) 19.7 m/s

WHICH STATEMENT IS TRUE?
a) An object moving in a circle will continue in circular motion when released.
b) An object in circular motion will fly out radially (curved straight outward) when released.
c) An object moving in circular motion will fly out tangent (straight line) to the circular path when released.

c) An object moving in circular motion will fly out tangent (straight line) to the circular path when released.

Through what angle will a point at the equator rotate after 6 hours?
a) 45
b) 90
c) 22.5
d) 180

b) 90

From Kepler's law of orbit, we can infer that the sun is located _____ of the planet's orbit.
a) at the center
b) at one of the foci
c) at both foci
d) anywhere along the semi-minor axis

b) at one of the foci

Kepler's laws of planetary motion replaced circular orbits with _____
a) elliptical orbits
b) parabolic orbits
c) conical orbits
d) hyperbolic orbits

a) elliptical orbits

Kepler's laws of planetary motion were proposed only for _____
a) our sun
b) any star in our galaxy
c) any star in the universe
d) stars of other solar systems

a) our sun

What does Kepler's law of period relate?
a) Time period and semi-minor axis
b) Time period and eccentricity
c) Time period and average radius of rotation
d) Time period and area swept by the planet

c) Time period and average radius of rotation

The velocity of a planet is constant throughout its elliptical trajectory in an orbit.
a) True b)False

b) false

The velocity of a planet is the greatest when it is
a) nearest to the sun
b) Farthest from the sun
c) at a point that is between the closest and farthest from the sun

a) nearest to the sun

The elliptical orbits of planets were indicated by calculations of the orbit of which astronomical body?
a) Mercury b) Earth c) Earth's moon d) Mars

d) Mars

If the eccentricities of the planetary orbits were taken as zero, then the
sun is at the center of the orbit.
a) True b) False

a) True

Kepler's First Law ( Law of Ellipses)

the path about the sun is elliptical in shape, with the center of the sun being located at one focus.