Physics Module 2

False

True or False: If the total displacement of an object is zero, the average speed of the object will be zero.

Displacement is a vector quantity describing the change in position, and distance traveled is the total length traveled

Which best describes the relationship between displacement and distance traveled?

Speed cannot be negative. The student has described the velocity of the bird in the y-direction

A student writes, "A bird that is diving for prey has a speed of −10 m/s ." What is wrong with the student's statement? What has the student actually described?

Yes, this is possible if the sign of the velocity vector is changing over a short time

Is it possible to have a velocity of zero yet an acceleration that is non-zero? Why?

Average speed. They would be the same if motion was all along a straight line in the same direction

If you divide the total distance traveled on a car trip (as determined by the odometer) by the time for the trip, are you calculating the average speed or the magnitude of the average velocity? Under what circumstances are these two quantities the same?

An odometer measures distance and the speedometer measures speed

Does a car's odometer measure displacement or distance? Does its speedometer measure speed or velocity?

The car has an acceleration due to the changing direction

A car turns a corner at a constant speed. Which statement is true:

39.2

You notice a very one-dimensional-thinking snail crawling along one rail of a railroad track. Naturally, you remove it to a safer place. But before you do, you observe it as it moves from position x_i = -90.1 cm to position x_f = -50.9 cm along the rail, as measured from a point where one rail abuts the next. What is the snail's displacement Δx in centimeters?

-2.14

A squirrel runs along an overhead telephone wire that stretches from the top of one pole to the next. The creature is initially at position x_i = 2.89 m, as measured from the center of the wire segment. It then undergoes a displacement of Δx = -5.03 m. What is the squirrel's final position x_f in meters?

108 m/s and 11.1 g

Assume that an intercontinental ballistic missile goes from rest to a suborbital speed of 6.50 km/s in 60.0 s
What is its average acceleration in m/s² and in multiples of g (9.80 m/s2)?

2 × 10 7 years

The North American and European continents are moving apart at a rate of about 3 cm/y. At this rate how long will it take them to drift 500 km farther apart than they are at present?

True

True or False: Kinematics can be defined as the study of motion without considering its causes.

1.43

A commuter backs her car out of her garage with an acceleration of 1.40 m/s². (a) How long (in seconds) does it take her to reach a speed of 2.00 m/s?

40 km/h and 34.3 km/h 25 S of E

A student drove to the university from her home and noted that the odometer reading of her car increased by 12.0 km. The trip took 18.0 min. (a) What was her average speed? (b) If the straight-line distance from her home to the university is 10.3 km in a direction 25.0^o south of east, what was her average velocity?

-0.0163

The well-fed ants of an ant colony maintain and adhere to a straight trail along the ground between the nearby picnic table and the hole leading to their underground nest, taken as the positive x-axis. One ant is observed first at position x_i = 9.63 m on the trail. Then it is seen staggering back and forth along the trail, eventually stopping at position x_f = 8.05 m exactly 96.7 s later. Find the average velocity along the x-axis of the ant during this time interval in m/s. Be sure to add a leading zero to your answer, if applicable.