Physics Gravitational Motion Exam

Describe the coordinate system that is usually chosen for analyzing rotational motion and state at least one advantage of this choice.

The polar coordinate system with the axis of rotation at the origin is used. Advantage: Positions are defined by a radius from the origin and an angle from the positive x- axis.

What position variable in rotational motion is analogous to the position variable in angular velocity

angular position (theta)

Describe a simpile method for determining the direction of the angular velocity vector of a rotating object.

The right hand rule.

What is torque? Give an example of torque in action

Torque is an effort to rotate a system around its pivot point. Ex. a wrench

Explain how something undergoing uniform circular motion can be accelerating

By going in circular motion, the object is constantly changing the direction of its speed.

What is the direction of the centripetal acceleration vector in circular motion

Towards the center of a circle

What does centripical mean?

center seeking

What measureable properties of a system undergoing circular motion determine the magnitude of centripical force

The radius of an objects path, its mass, and its tangential speed.

What long-held beliefs about the motions of the planets did Kepler have to discard in order to develop his laws.

The idea that planets move at a constant speed in a circular motion.

Kepler’s first law of planetary motion

Planets and other objects orbit the sun in elliptical orbits.

Kepler’s second law of planetary motion

The planets move in such a way that the line between the sun and the planet covers equal areas of a planet’s orbit in equal time intervals.

Kepler’s second law of planetary motion

For each system of objects orbiting a central object, the ration of the cube of the semi-major axis and the square of the period is a constant.

What restriction applies to the use of Kepler’s constants?

A Keplerian constant is for a specific orbital system. Each system has its own value.

A less massive falling object will not accelerate toward a planet as much as a more massive object

False, a = F/m, as F becomes greater, it is divided by the higher mass to have the same acceleration as before.

s =

r(theta)

w =

vt/r

Why does the complete coordinate system of a rotating object include the z axis?

The rotational axis is parallel to the z-axis.

The angular velocity and acceleration vectors are also parallel to the z axis.