What must be true if an object is speeding up in a straight line? The x component of the acceleration must be negative. The direction of the acceleration is the same as the direction of the velocity. O The acceleration is perpendicular to the velocity. O The direction of the acceleration is opposite the direction of the velocity. O The x component of the acceleration must be positive.

What must be true if an object is speeding up in a straight line? The x component of the acceleration must be negative. The direction of the acceleration is the same as the direction of the velocity. O The acceleration is perpendicular to the velocity. O The direction of the acceleration is opposite the direction of the velocity. O The x component of the acceleration must be positive.

Physics for Scientists and Engineers: Foundations and Connections

1st Edition

ISBN:9781133939146

Author:Katz, Debora M.

Publisher:Katz, Debora M.

Chapter4: Two-and-three Dimensional Motion

Section: Chapter Questions

Problem 11PQ

See similar textbooks

Similar questions

Cars A and B each move to the right with constant acceleration along a straight road. The velocity vectors of each car are shown in Figure P2.78 for several times separated by equal time intervals. For the entire interval from time t1 to time t4, car B is ahead of car A (that is, car B is to the right of car A), a. Is the acceleration of car B to the left, to the right, or zero? Explain. b. Is the magnitude of the acceleration of car A greater than, less than, or equal to the magnitude of the acceleration of car B? Explain your reasoning, c. Is the distance between car A and car B at time t3 greater than, less than, or equal to the distance between car A and car B at time t2? Explain.
An Australian emu is running due north in a straight line at a speed of 13.0 m/s and slows down to a speed of 9.40 m/s in 4.20 s. (a) What is the magnitude and direction of the bird’s acceleration? (b) Assuming that the acceleration remains the same, what is the bird’s velocity after an additional 1.20 s has elapsed?
(a) Is it possible for speed to be constant while acceleration is not zero? Give an example of such a situation. (b) Is it possible for velocity to be constant while acceleration is not zero? Explain. Give an example in which velocity is zero yet acceleration is not. (d) If a subway train is moving to the left (has a negative velocity) and then comes to a stop, what is the direction of its acceleration? Is the acceleration positive or negative? *Can you answer all three parts?*
A rugby player passes the ball 7.00 m across the field, where it is caught at the same height as it left his hand. (a) At what angle was the ball thrown if its initial speed was 12.0 m/s, assuming that the smaller of the two possible angles was used? (b) What other angle gives the same range, and why would it not be used? (c) How long did this pass take?
A) If an object is thrown horizontally, travels with an average x-component of its velocity equal to 5 m/s, and does not hit the ground, what will be the x-component of the displacement after 20 s? B) What will be it's velocity in the y-direction (downward)? c) How far will the object have travelled downward?
A rhinoceros is at the origin of coordinates at time t1 = 0. For the time interval from t1 to t2 = 11.0 s, the rhino's average velocity has x-component - 4.20 m/s and y-component 5.10 m/s. a. At time t2 = 11.0 s what is the x-coordinate of the rhino? b. At time t2 = 11.0 s what is the y-coordinate of the rhino? c. How far is the rhino from the origin?
A rhinoceros is at the origin of coordinates at time t1 = 0. For the time interval from t1 = 0 to t2 = 12.0 s, the rhino’s average velocity has x-component -3.8 m/s and y-component 4.9 m/s. At time t2 = 12.0 s, (a) what are the x- and y-coordinates of the rhino? (b) How far is the rhino from the origin?
An SR-71 reconnaissance aircraft, the world's fastest aircraft, is flying east at 3000 km/h. a. If the plane encounters a crosswind of 300 km/h that is directed to the north, what is the magnitude and direction with resultant velocity? b. If the border lies along a straught north/south line, will it take the plane, more, less, or the same amount of time to reach the eastern border if there were no crosswind?
d) Calculate the instantaneous acceleration as a function of time e) Calculate my instantaneous acceleration at (i) t=0s and (ii) t=2s f) Calculate my displacement vector for the interval t=0 to 2.0 seconds
A football quarterback is moving straight backward at a speed of 2.00 m/s when he throws a pass to a player 18.0 m straight downfield. (a) If the ball is thrown at an angle of 25° relative to the ground and is caught at the same height as it is released, what is its initial speed relative to the ground? (b) How long does it take to get to the receiver? (c) What is its maximum height above its point of release?
Given the displacement vector ? =[3.1?2, 2.0?, 0]:(a) what is the position of the object at time? = 2.1 ? assuming the object started at theorigin?(b) what is the distance the object has traveled at? = 2.1 ??(c) what is the velocity of the object as a functionof time?(d) what is the velocity of the object at ? = 0, ? =2.1 ? and ? = 4.2 ??(e) what is the speed of the object at the timesgiven in part (d). Are the speed evenly spaced?Would you expect this? Why or why not?(f) what is the acceleration of the object at? = 0, ? = 2.1 ? and ? = 4.2 ??
Bryan Allen pedaled a human-powered aircraft across the English Channel from the cliffs of Dover to Cap Gris-Nez on June 12, 1979. (a) He flew for 169 min at an average velocity of 3.53 m/s in a direction south of east. What was his total displacement? (b) Allen encountered a headwind averaging 2.00 m/s almost precisely in the opposite direction of his motion relative to the Earth. What was his average velocity relative to the air? (c) What was his total displacement relative to the air mass?