Chapter 2, Earth Space Science

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

An object is in free fall. At one instant, it travels at a speed of 50 m/s. Exactly 1 second later, its speed is about

60 m/s

A car accelerates at 2 meters/s/s.What is its speed 3 seconds after the car starts moving?

6m/s

Which has the greatest density: 1 kg of feathers, 1 kg of lead, 10 kg of feathers?

1 kg of lead

The vertical height attained by a basketball player who achieves a hang time of a full 1 s is about

1.2 m

A 1-kg mass at Earth's surface weighs about

10 N

The force of friction on a sliding object is 10 N/ The applied force needed to maintain a constant velocity is

10 N

When a 10-N object is suspended at rest by a vertical strand of rope, the tension in the rope is

10 N

A pot falls from a ledge and hits the ground 45 m below. The speed with which is hits the ground is about

30 m/s

A man weighing 800 N stands at rest on two bathroom scales so that one scale shows a reading of 500 N. The reading on the other scale is

300 N

If a baseball being thrown goes from zero to 30 m/s in 0.1 s, what is its average acceleration?

300 m/s^2

An apple falls from a tree and hits the ground 5 m below. It hits the ground with a speed of about

10 m/s

Disregarding air drag, how fast must you toss a ball straight upward in order for the ball to remain in the air for a total time of 2 s?

10 m/s

Neglecting air resistance, when you toss a rock upward, by about how much does its upward speed decrease each second?

10 m/s

The gain in speed each second for a freely falling object is about

10 m/s.

If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by

10 m/s..

A ball is thrown 125 m upward and then falls the same distance back to the Earth. Neglecting air resistance, its total time in the air is about

10 seconds

Ten seconds after starting from rest, a free falling object on Earth will have a speed of about

100 m/s

How much tension is there in a rope that holds a 13 N bag of apples at rest?

13N

The average speed of a horse that gallops a distance of 10 km in a time of 30 min is

20 km/h

A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is

400 N

An object is pulled with two forces: 5 N North and 10 N South. The magnitude of the net force is (opposites SUBTRACT)

5 N

Suppose a jumper claims a hang time of 2 s. Then that jumper must be able to jump at a height of

5 m

One half after starting from rest, a freely falling object will have a speed of about

5 m/s

A freely falling object has a speed of 40 m/s at one instant. Exactly one second later it's speed will be

50 m/

An object is pulled northward with a force of 10 N and southward with a force of 15 N. The magnitude of the net force on the object is

5N

If a car increases its velocity from 0 to 60 km/h in 10 s, its acceleration is

6 km/h*s

What equation shows the relationship among velocity, time, and acceleration?

Acceleration=change in velocity/time interval

Did Aristotle believe that forces are necessary to keep moving objects moving, or did he believe that, once moving, they would move more themselves?

Aristotle believed that forces are necessary to keep objects moving.

What quantities are necessary to determine a vector quantity?

Direction and magnitude

Which dominated Galileo's way of extending knowledge, philosophical discussion or experiment?

Experiment

The scientist to first introduce the concept of inertia was

Galileo

What is the name of the property of objects to maintain their states of motion?

Inertia

Does the speedometer on a vehicle show average speed or instantaneous speed?

Instantaneous speed

Where would your mass be greater, on the moon or on Earth?

Mass is the same everywhere.

What were Aristotle's two main classifications of motion?

Natural and Violent motion

Which has the greater density, 1kg of water or 10kg of water?

Neither, since any amount of water has the same density.

One kg weighs N on earth. Would it weight more or less on the moon?

One kg would weight less on the moon

How does the direction of a friction force compare with the direction of motion of a sliding object?

The direction of friction is opposite to the direction of motion.

If we push a crate at a constant velocity, how does the friction on the crate compare with out pushing force? The pushing force and the surface are horizontal.

The friction force acting on the crate is equal to the pushing force and has the opposite direction.

When you toss a ball upward, by how much does its upward speed decrease each second?

The speed decreases by 10 m/s each second

When you weigh yourself, how does the support force of the scale acting on you compare with the gravitational force between you and Earth?

The support force is equal to the gravitational force and has the opposite direction

Why does the unit of time appear twice in the definition of acceleration?

The unit of time appears once for the unit of velocity, and again for the time during which the velocity changes.

What does ⅀F = 0 mean?

The vector sum of all the forces that act on an object equals zero. The forces cancel!

Why do we say that velocity and speed is not a vector?

Velocity involves both magnitude and direction. Speed involves only magnitude.

Which depends on gravity, weight or mass?

Weight

Suppose you push on a heavy crate, but not hard enough to make it slide. Does a friction force act on the crate?

Yes, opposite to your push, just enough so that f=0

Suppose you push on a heavy crate, but not hard enough to make it slide. Does a friction act on the crate?

Yes, opposite to your push, just enough so that ⅀F =0

Where would your weight be greater, on Earth or the moon?

Your weight would be greater on Earth because its force of gravity is stronger.

Hang from a pair of gym rings and the upward support forces of the rings will always

add up to equal your weight.

An object in mechanical equilibrium is an object

at rest or moving with constant motion

An object _____ has zero acceleration.

at rest, moving at constant velocity, in mechanical equalilbrium

Which has greater mass, a king size pillow, an automobile battery, or both?

automobile battery

Drop a rock from a 5 m height and it accelerates at 10 m/s^2 and strikes the ground 1 s later. Drop the same rock from a height of 2.5 m and its acceleration of fall is

the same

A motorcycle undergoes acceleration when it

changes speed or direction

The two measurements necessary for calculating average speed are

distance and time

Whereas Aristotle relied on logic in explaining nature, Galileo relied on

experiment

If a freely falling object were somehow equipped with a odometer to measure the distance it travels, then the amount of distance it travels each succeeding seconds would be

greater than the second before

An object that has twice as much mass as another objects also has twice as much

inertia

One object has twice as much mass as another object, and also has twice as much

inertia

A bullet is dropped into a river from a very high bridge. At the same time, another bullet is fired from a gun, straight down towards the water. Neglecting air resistance, the acceleration just before striking the water

is the same for each bullet

Whenever the net force on an object is zero, its acceleration

is zero

A ball is rolling down an inclined plane. How does the distance traveled by the ball in the second half second compare with the distance traveled by the ball in the first half second?

it increases

When Galileo rolled a ball down an incline and up another incline, he found that the ball rolled nearly to

its initial height

The hang time of professional basketball players is typically

less than 1 s

A kilogram is a measure of an objects

mass

Density is the ratio of

mass/volume

What equation shows the relationship among speed, distance and time?

speed=distance covered/time traveled

Your weight is

the gravitational attraction between you and the earth

Compared with the mass of a certain object on Earth the mass of the same object on the moon is

the same

Someone standing at the edge of a cliff throws one ball straight up and another ball straight down at the same initial speed. Neglecting air resistance, the ball to hit the ground below the cliff with the greater speed will be the one initially thrown

they will both hit with the same speed.

If you push on a heavy crate to the right and it slides, what is the direction of friction on the crate?

to the left

Which direction does a table push a book resting on it?

up


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