physical science ch 3

The essentials of the first law of motion were initially developed by

Galileo.

A spacecraft in space keeps going at the same velocity, even without firing its rockets, in accordance with the _______________ law of motion.

first

In the equation A = B/C, the A and C are _______________ proportional

inversely

"Weightlessness" occurs when an object

is in free fall.

The SI base units making up the newton are

kg-m/s2.

The speed of a comet in its orbit around the Sun is ______________ when its distance from the Sun is greatest.

least

According to Newton's second law, the force required to accelerate an object is equal to its

mass times the acceleration.

The angular momentum of a body is constant if the

net torque is zero.

"For every action there is an equal and opposite reaction" is a statement of Newton's

third law.

Two equal and opposite forces of 5.0 N act on an object. The unbalanced force on the object is

0 N.

Explain what momentum is & how it is conserved in a collision.

1. the quantity of motion of a moving body, measured as a product of its mass and velocity 2. the impetus gained by a moving object Linear momentum of the system is conserved; it doesn't change with time. With no balanced forces no acceleration occurs, so there is no change in velocity or momentum.

what are Newton's 3 Laws of Motion? Give examples

1st law-an object will remain at rest or in universal form motion in a straight-line unless acted on by an external, unbalanced force. Ex: If you are in a car & you were to stop immediately you would continue to go forward as fast as your car was going. 2nd law- The acceleration of an object is equal to the net force on the object divided by the mass of the object. Ex 1: pushing a ball. The velocity goes from zero to how hard you push the ball. Ex 2: pushing a 5 & 10 lb ball as hard as you can. The 10 lb ball would accelerate less because it has more mass. 3rd law- For every action there is an equal & opposite reaction; for every force there is an equal & opposite force, acting on different bodies. Ex: when you sit on a chair, your body exerts a downward force on the surface of the chair, while the chair exerts an equal & upward force on your body. As both are balanced, the chair & you stay in the same position.

If a person weighs 120 lbs on the Earth, her weight on the Moon would be

20 lbs

The constant G that appears in the equation F = Gm1m2/r2 is

a universal constant.

A constant net force acting on an object that is free to move will produce a constant

acceleration.

The acceleration of an object acted on by a net force perpendicular to the direction of the object's original motion

all of these---1. is described by Newton's laws. 2. causes a change in direction 3. causes a change I velocity

The acceleration produced by an unbalanced force acting on an object is

all of these-1.inversely proportional to the mass of the object. 2. in the direction of the force. 3. directly proportional to the magnitude of the force.

A mass is accelerated when ______________ acts upon the mass.

an unbalanced force

The quantity mvr is an object's

angular momentum.

Newton's third law of motion states that the force pair acting on different objects consists of two forces that

are equal and in opposite directions.

To cause an object to move in a circle, a(n) ______________ force is necessary.

centripetal

Mass and weight on the Earth's surface

differ in magnitude by a constant.

In the equation A = B/C, the A and B are _______________ proportional.

directly

Linear momentum

has magnitude and direction.

When a net force on a moving object increases, the object will

have a change in speed and/or direction.

Explain what Archimedes' Principle is

indicates that the upward buoyant force that is exerted on a body fully or partially submerged in fluid, is equal to the weight of the fluid that the body displaces.

Mass is a measure of

inertia

The natural tendency of an object to remain at rest or in motion with a constant velocity is called

inertia

Newton's law of universal gravitation is believed to be applicable

throughout the universe.

What must be exerted on an object to change the angular momentum?

torque

The total linear momentum of an isolated system of masses remains the same if there are no external ______________ acting on the system.

unbalanced forces

The linear momentum of an object can be determined by taking the product of the mass and the

velocity of the object.

The relationship between mass and weight is given by the equation

w = mg.

Which of the following would be different for a person on the Moon rather than on the Earth?

weight

An automobile travels due north with a constant speed of 90 km/h. The unbalanced force acting on the auto with respect to the highway is

zero.