CHAPTER 2: LINEAR MOTION

Question 1

How can I remember the relationship between time, distance and velocity?

Answer 1

My dog is in Vermont.

Which is odd because,

my dog’s name is Vermont.

d = VT

Question 2

What are the three equations you can get from “My dog is in Vermont?”

Answer 2

1. d=vt

(then move the v then the t)

2. d/v =t
3. d/t=v

Question 3

Why do we say motion is relative?

Answer 3

You can only measure the motion of an object by relating it to another object. We are always in motion: spinning ‘round the earth, ‘round the sun, ‘round the galaxy, and away form all other matter in the universe!!!! So we generally measure motion relative to the earth.

Question 4

About how fast do people walk in m/s? (mph?) [km/h?]

Answer 4

1-2 m/s (2-5mph) [3-6km/h]

Question 5

About how fast do people run in m/s? (mph?) [km/h?]

Answer 5

4-6 m/s (9 - 15 mph) [15- 20 km/h]

Question 6

How fast is the fasted human in m/s? (mph?) [km/h?]

Answer 6

over 10 m/s ! (25 mph +) [35 km/h +]

Question 7

How fast do cars travel in m/s? (mph?) [km/h?]

Answer 7

15 m/s backroad, 30 m/s on highway (35 mph and 70 mph) [50-100 km/h]

Question 8

How fast are airplanes in m/s? (mph?) [km/h?]

Answer 8

250+ m/s (500+ mph) [800+km/h]

Question 9

1 meter per second is about ______ mph and about ____ km/h

Answer 9

1 m/s = 2.2 mph = 3.6 km/h (about 1 m/s = 2 mph = 3 km/h)

Question 10

What is speed?

Answer 10

how much distance is covered over a period of time

Question 11

Instantaneous speed vs. average speed?

Answer 11

Instantaneous speed is what you see on a car’s speedometer. It is the speed an object is traveling at one moment in time. The average speed is the average speed of an entire trip, the average speed over an amount of time.

Question 12

How is velocity different from speed?

Answer 12

50 m/s is a speed. 50 m/s NORTH is a velocity. Velocity is speed with direction.

Question 13

What is acceleration? give a example.

Answer 13

Acceleration is a CHANGE OF VELOCITY. Example: In a car you increase your speed from 30 km/h to 50 km/h over a period of 4 seconds. Your speed changed 20 km/h over a period of 4 seconds. Your ACCELERATION was (20 km/h) / (4 s) = 5 km/ h/ s. Your speed increased 5 km/h each second.

Question 14

How can you change velocity when driving? (three ways)

Answer 14

Hitting the gas (speeding up), hitting the brakes (slowing down) or TURNING. A change in direction is a change in velocity.

Question 15

When have you felt acceleration?

Answer 15

In a car when you speed up (pulled back), slow down (pulled forward) or turn (pulled away from turn direction).

Question 16

What did Galileo discover at the leaning tower of Pisa?

Answer 16

That all objects accelerate towards earth at the same rate, regardless of the mass of the object (when you ignore air resistance).

Question 17

What did Galileo discover from ramps and marbles?

Answer 17

That the distance an object travels, due to gravity, is directly related to the SQUARE of the time it travels.

Question 18

What is the acceleration due to gravity at the earth’s surface?

Answer 18

about 10 m/s2 (actually 9.8 m/s2)

Question 19

If you throw a ball straight up, what is the velocity at the very top?

Answer 19

zero

Question 20

If you throw a ball straight up, what is the acceleration at the very top?

Answer 20

10 m/s2 this acceleration is forever present at the earth’s surface

Question 21

If you drop a ball from rest, how fast is it moving after 1s ? 2s ? 5s?

Answer 21

final velocity = 10(time). So… 10 m/s, 20m/s and 50m/s

Question 22

If you drop a ball from rest, what is avg speed after 1s ? 2s ? 5s?

Answer 22

avg speed = (start speed + end speed) / 2 From rest we can simply say “avg speed= 5 t” So…. 5m/s, 10m/s and 25 m/s

Question 23

If you drop a ball from rest, how far did it go after 1s ? 2s ? 5s?

Answer 23

distance is always “avg velocity times time” From rest we can say “distance = 5t2” So, 5m, 20m, 125m

Question 24

If you throw a ball up at 80m/s, how long till it reaches the top?

Answer 24

8 seconds

Question 25

If you throw a ball up at 80m/s, what will be average speed on the way up?

Answer 25

(80 + 0 ) / 2 = 40 m/s

Question 26

If you throw a ball up at 80m/s, how far up will it go?

Answer 26

40 m/s (8 seconds) = 320 meters

Question 27

If you throw a ball up at 80m/s, how fast will it be going when you catch it?

Answer 27

80 m/s

Question 28

If you throw a ball up at 80m/s, how long will it be in the air before you catch it?

Answer 28

16 seconds

Question 29

If you are driving at 40 km/h and speed up to 60 km/h over 10 seconds, what was your acceleration?

Answer 29

Your speed changed 20 km/h over 10 seconds, so (20 km/h / 10 s) = 2 km/h/s. You increased your speed 2 km/h each second.

Question 30

What does it mean by 10m/s2 ? Explain the “second squared” part

Answer 30

It is actually not really a squared second. Think of it as “10 m/s per second.” Velocity increases by 10 m/s for every second an object falls towards earth.

Question 31

Give example of what accelerating at 10m/s2 means

Answer 31

If an object is falling at a specific time at a speed of 50 m/s, it will be falling 60 m/s a second later, and 70 m/s a second after that.

Question 32

Give an example of what accelerating at 5 km/h/s means

Answer 32

If an object is moving at 20 km/h, it will be moving 25 km/h a second later and 30 km/h a second after that.