# Physics

1.1/3 points | Previous AnswersSerPSE8 2.P.010.My Notes |

Question Part

Points

Submissions Used

A car travels along a straight line at a constant speed of 41.5 mi/h for a

distance d and then another distance d in the same direction at another constant speed. The average velocity for the entire trip is 25.0 mi/h.

(a) What is the constant speed with which the car moved during the second

distance d?

Your response is within 10% of the correct value. This may be due to roundoff

error, or you could have a mistake in your calculation. Carry out all intermediate

results to at least four-digit accuracy to minimize roundoff error. mi/h

(b) Suppose the second distance d were traveled in the opposite direction; you forgot something and had to return home at the same constant speed as found

in part (a). What is the average velocity for this trip?

Your response differs significantly from the correct answer. Rework your solution

from the beginning and check each step carefully. mi/h

(c) What is the average speed for this new trip?

mi/h

2.–/3 pointsSerPSE8 2.P.013.My Notes |

Question Part

Points

Submissions Used

A velocity—time graph for an object moving along the x axis is shown in the figure. Every division along the vertical axis corresponds to 2.00 m/s and each

division along the horizontal axis corresponds to 2.50 s.

(a) Plot a graph of the acceleration versus time.

This answer has not been graded yet.

(b) Determine the average acceleration of the object in the following time

interval t = 12.5 s to t = 37.5 s. m/s2

(c) Determine the average acceleration of the object in the following time

interval t = 0 to t = 50.0 s. m/s2

3.–/3 pointsSerPSE8 2.P.016.WI.My Notes | A particle starts from rest and accelerates as shown in the figure below.

(a) Determine the particle’s speed at t = 10.0 s. m/s

Determine the particle’s speed at t = 20.0 s? m/s

(b) Determine the distance traveled in the first 20.0 s. (Enter your answer to one

decimal places.)

m

4.–/3 pointsSerPSE8 2.P.017.MI.My Notes |

A particle moves along the x axis according to the equation x = 1.99 + 2.99t − 1.00t2,

where x is in meters and t is in seconds. (a) Find the position of the particle at t = 2.50 s. m

(b) Find its velocity at t = 2.50 s. m/s

(c) Find its acceleration at t = 2.50 s. m/s2

5.–/2 pointsSerPSE8 2.P.020.My Notes | Draw motion diagrams for the following items. (Do this on paper. Your instructor

may ask you to turn in your work.)

(a) an object moving to the right at constant speed

(b) an object moving to the right and speeding up at a constant rate

(c) an object moving to the right and slowing down at a constant rate

(d) an object moving to the left and speeding up at a constant rate

(e) an object moving to the left and slowing down at a constant rate

This answer has not been graded yet.

(f) How would your drawings change if the changes in speed were not uniform;

that is, if the speed were not changing at a constant rate?

This answer has not been graded yet.

6.–/5 pointsSerPSE8 2.P.021.My Notes | A parcel of air moving in a straight tube with a constant acceleration of –

4.10 m/s2 and has a velocity of 13.5 m/s at 10:05:00 a.m.

(a) What is its velocity at 10:05:01 a.m.?

m/s

(b) What is its velocity at 10:05:04 a.m.?

m/s

(c) What is its velocity at 10:04:59 a.m.?

m/s

(d) Describe the shape of a graph of velocity versus time for this parcel of air.

This answer has not been graded yet.

(e) Argue for or against the following statement: “Knowing the single value of an

object’s constant acceleration is like knowing a whole list of values for its

velocity.”

This answer has not been graded yet.

7.–/3 pointsSerPSE8 2.P.024.MI.My Notes | We investigated a jet landing on an aircraft carrier. In a later maneuver, the jet

comes in for a landing on solid ground with a speed of 95 m/s, and its

acceleration can have a maximum magnitude of 5.52 m/s2 as it comes to rest.

(a) From the instant the jet touches the runway, what is the minimum time

interval needed before it can come to rest?

s

(b) Can this jet land on a small tropical island airport where the runway is 0.800

km long?

Yes No

(c) Explain your answer.

This answer has not been graded yet.