Review Questions and practice test questions.

Chapter 2: Linear Motion.

 

  1. How do you calculate average speed?

Average speed = distance/time

  1. What is displacement?

Distance from starting point (a round trip has a displacement of zero)

  1. What is velocity?  What are the units?

Velocity is speed AND direction

  1. What is acceleration?    What are the units?

Acceleration is the rate of change of velocity                        a =∆v/t

  1. What does the speedometer on your car tell you? Average or instantaneous speed?

Instantaneous speed

  1. What is the acceleration if there is no change in velocity?

zero

  1. What is the acceleration due to gravity ‘g’?

10 m/s2

  1. What is the acceleration of a car that goes from 0 km/h to 100 km/h in 10 sec?

10 km/h.s

  1. What are the three devices that control the acceleration of a car?

Gas pedal, brake, and steering wheel

  1. What does the idea of relative motion say about non-motion?

Non motion can’t happen, because it can look like motion to something moving at a constant or changing speed.

  1. What is ‘g’?

.. g is the acceleration due to gravity at the surface of the earth.

  1. What is the velocity of a freely falling object after 5 seconds?

V = gt = 50 m/s

  1. What hits the ground first, a feather or a hammer, neglecting air resistance?

Neither, they hit the ground at the same time!

  1. What is the formula for distance during free fall?

D = ˝ gt2 or d = 5t2

  1. If a rock is thrown straight up at 40m/s, how long will it remain in the air?          

T = v/a t = 40/10 = 4      4sec up and 4 sec down.  T = 8 seconds

How high will it go? 

Max height = 5t2 = 5 (4)2 = 80m.  

How high will it be after 6 sec?

Up for 4 seconds = 80 meters

Down for 2 seconds = 5(2)2 = 20 meters

80 meters – 20 meters = 60 meters above ground.

 

  1. If a baseball is thrown upward at 30 m/s, how long will it take to reach the top of its path?
    1. 3 seconds

What is the speed when it hits the ground?

30 m/s

How fast is it going after 2 sec?

            10 m/s upwad

  1. What is the ACCELERATION of an object thrown straight upward when it reaches the top of its path?

10m/s2

What is the velocity at that point?

      0 m/s

  1. What does the slope of a distance vs. time graph tell you if it is positive, negative or zero?

Slope of a distance vs. time graph is VELOCITY.  Positive slope is positive velocity (forward motion).  Negative slope is negative velocity(backward motion).  Zero slope is zero velocity(at rest)

  1. What does the slope of a velocity vs. time graph tell you if it is positive, negative, or zero?

Slope of a velocity vs. time graph is Acceleration. 

 

 

 

 

 

 

Calculations.

  1. If you travel 0.5 hours at an average speed of 60 km/h how far will you have traveled?

D = vt

D = 60 x 0.5 = 30 miles

  1. If a plane flies 600km/h, for 2 hours, how far does it fly?

D = vt

D = 600 x 2 = 1200km

  1. What distance does a car travel if it goes North at 50 km/h for 2 hours and South at 50 km/h for 2 hours?

D = speed x time

D = 50 x 4 = 200km. 

Note:  direction only matters if we ask about displacement. 

  1. What is the acceleration of a car that goes from 0 km/h to 100 km/h in 5 sec?

A = ∆v/t

A = 100/10

A = 10km/h s

  1. How long does an object stay in the air when it is thrown upward at 50 m/s?

10 sec (5 up and 5 down)

  1. How high did someone jump who had a hang time of 0.4 sec?

Free fall time is 0.2 sec          

D = 5t2

D = 5 (0.2)2 = 0.2 meters

  1. What is bigger 45,000,000,000 or 4.5 x 1011

4.5 x 1011 is bigger.

 

Review.

 

1.      Do you understand the worksheet “interpreting graphs?”

2.      Do you understand all of the worksheet “free fall questions”

3.      Do you understand all questions on the worksheets C-D 2.1 and 2.2?

4.      Do you understand the homework problems from the book, chapter 2 review, plug’n’chug and think and solve?

5.      Good luck!

 

Graph skills

 

1.      A ball is thrown straight up, then returns to earth a few seconds later.

a.       Draw the Distance vs. time graph for this (see book pg.23)

b.      Draw the Velocity vs. time graph for the ball.

c.       Draw the acceleration vs. time graph for the ball.

 

Answer in class.