Physics Lecture 2

For which one of the following situations will the path length equal the magnitude of the displacement? A) A toy train is traveling around a circular track. B) A ball is rolling down an inclined plane. C) A train travels 5 miles east before it stops. It then travels 2 miles west. D) A ball rises and falls after being thrown straight up from the earth's surface. E) A ball on the end of a string is moving in a vertical circle.

B

Here is a motion diagram of a car moving along a straight road: "constant slower speed and passes a zero mark and then speeds up to a faster constant speed" Which position-versus-time graph matches this motion diagram? A) straight line intercepting 0 B) steep line, intercept 0, steeper line C) very steep line, intercept 0, less steep line D) above zero, steep line, then gets steeper

B

The slope at a point on a position-versus-time graph of an object is A) The object's speed at that point. B) The object's velocity at that point. C) The object's acceleration at that point. D) The distance traveled by the object to that point. E) I am not sure.

B

If a bird is moving at 3.5 m/s at a certain instant of time, then it will travel 3.5 m in the next second.

F

The change in the position vector of a moving object is equal to the distance it has moved.

F

A sports car has an average acceleration of 13.1 miles/hour*second. How long does it take for the car to reach 60.0 mi/h, if it starts from rest? A) 4.6 s B) 5.5 s C) 3.1 s D) 8.8 s

A

A 8.7 hour trip is made at an average speed of 73.0 km/hr. If the first third of the trip (chronologically) was driven at 96.5 km/hr, what was the average speed for the rest of the journey? A) 61 km/hr B) 51 km/hr C) 67 km/hr D) 85 km/hr

A

A car travels 95 km to the north at 70.0 km/h, then turns around and travels 21.9 km at 80.0 km/h. What is the difference between the average speed and the average velocity on this trip? A) 27 km/h B) 19 km/h C) 32 km/h D) 24 km/h

A

At time t = 0 s, an object is observed at x = 0 m; and its position along the x axis follows this expression: x = -4t + t2, where the units for distance and time are meters and seconds, respectively. What is the object's displacement x between t = 1.0 s and t = 3.0 s? A) +16 m B) -21 m C) +10 m D) +2 m E) -5 m

A

If the fastest you can safely drive is 65 mi/h, what is the longest time you can stop for dinner if you must travel 541 mi in 9.6 h total? A) 1.3 h B) 1.4 h C) 1.0 h D) You can't stop at all.

A

A particle travels along a curved path between two points P and Q as shown. The displacement of the particle does not depend on: A) the location of P. B) the location of Q. C) the distance traveled from P to Q. D) the shortest distance between P and Q. E) the direction of Q from P.

C

Here is a motion diagram of a car moving along a straight road: "constant slower speed and passes a zero mark and then speeds up to a faster constant speed" Which velocity-versus-time graph matches this motion diagram? A) steep angled line, halfway gets steeper B) very steep angled line, halfway gets less steep C) horizontal line, halfway goes vertical, then horizontal D) horizontal line, halfway gets angled

C

You walk from your house to the store 1.0 km in 25 minutes, and then you spent 10 minutes in the store. In your way back home you stop after 15 minutes walking in your friend house, which is located at 0.76 km from the store. Your displacement was: A) 760 m B) 1000 m C) 240 m D) 1760 m

C

Which of the following statements about speed is not true? A) Instantaneous speed is equivalent to instantaneous velocity B) Average speed is the total distance traveled divided by the total time C) Speed is an scalar quantity D) Speed can be zero, negative and positive

D

Which of the following statements about velocity is not true? A) Average velocity is the displacement of an object divided by the time interval B) Velocity is a vector quantity C) It measures how fast and in what direction the particle is moving D) Velocity is always a positive quantity

D

You walk from your house to the store 1.0 km in 25 minutes, and then you spent 10 minutes in the store. In your way back home you stop after 15 minutes walking in your friend house, which is located at 0.76 km from the store. Your average speed was: A) 10 m/s B) 1.0 m/s C) 0.15 m/s D) 0.59 m/s

D

A car travels in a straight line covering a total distance of 90.0 miles in 60.0 minutes. Which one of the following statements concerning this situation is necessarily true? A) The velocity of the car is constant. B) The acceleration of the car must be non-zero. C) The first 45 miles must have been covered in 30.0 minutes. D) The speed of the car must be 90.0 miles per hour throughout the entire trip. E) The average velocity of the car is 90.0 miles per hour in the direction of motion.

E

A motorist makes a trip of 180 miles. For the first 90 miles she drives at a constant speed of 30 mph. At what constant speed must she drive the remaining distance if her average speed for the total trip is to be 40 mph? A) 45 mph B) 50 mph C) 52.5 mph D) 55 mph E) 60 mph

E

If the average speed of an object is zero, then its average velocity must be zero; but if its average velocity is zero, its average speed is not necessarily zero.

T

If the final position vector of a moving object has a smaller magnitude than the initial position vector, then the change in the object's position vector has a positive magnitude.

T

It is not physically possible for the "position versus time" graph of a moving animal to be either perfectly vertical or perfectly horizontal.

T