Physics Test 3.4 & 4.1

A duck maintains a constant swimming speed of 0.50 m/s relative to the water. As it swims across a creek that has a constant downstream current of 0.30 m/s, a naturalist sitting on the bank observes its motion. What is the duck's speed as observed by the naturalist?

0.58 m/s

Sequence the steps in drawing a free-body diagram

1. Identify the forces acting on the body and the direction of the forces. 2. Draw a diagram to represent the isolated object. 3. Draw and label force vectors for all the external forces acting on the object.

In a circus parade, a clown standing on a float moving at a constant forward speed drops a fake dumbbell. A child in the bleachers on the sidewalk observes the dumbbell. Ignore air resistance. // Who would observe the dumbbell falling straight down? a. the clown only b. the child only c. both the clown and the child d. neither the clown nor the child

a. the clown only

In a circus parade, a clown standing on a float moving at a constant forward speed drops a fake dumbbell. A child in the bleachers on the sidewalk observes the dumbbell. Ignore air resistance. // The dumbbell's motion as described by an acrobat walking in the parade is very similar to the clown's description of the dumbbell's motion. What do you know about the motion of the acrobat? a. The acrobat is at rest with respect to the clown. b. The acrobat is at rest with respect to the float. c. both A and B d. neither A nor B

c. both A and B

A force unit is defined as the product of a mass unit and a unit of a. time. b. displacement. c. velocity. d. acceleration

d. acceleration

In a circus parade, a clown standing on a float moving at a constant forward speed drops a fake dumbbell. A child in the bleachers on the sidewalk observes the dumbbell. Ignore air resistance. // The clown and the child would agree about which of the following observations? a. the time interval for the dumbbell to fall b. the vertical distance the dumbbell falls c. the initial vertical velocity of the dumbbell d. all of the above

d. all of the above

In a circus parade, a clown standing on a float moving at a constant forward speed drops a fake dumbbell. A child in the bleachers on the sidewalk observes the dumbbell. Ignore air resistance. // Who would observe the dumbbell falling backward? a. the clown only b. the child only c. both the clown and the child d. neither the clown nor the child

d. neither the clown nor the child

What is a frame of reference?

the perspective to look at an object's displacement.

Explain the ideas of contact forces and field forces.

Contact forces require touching; field forces work at a distance and no touching is required

What is force AND describe the unit of force?

Force is an action exerted on an object that may change the objects state of rest/ or motion. The unit is the Newton (1 m/s^2= 1N = 1 kg x 1m/s^2

Compare and contrast motion in one and two dimensions.

In one dimension, there is one plane; in two dimensional motion there are two planes.

Explain that to describe two motions, you need to discuss what they have in common.

You need to discuss that they both have changed places/ been displaced; you can also tell from your perspective.

Units that measure weight are units of a. acceleration. b. force. c. mass. d. velocity

b. force

Which of the following statements describe free-body diagrams? I. Force diagrams show force vectors as arrows. II. Forces exerted on the object are represented. III. Forces exerted by the object are represented. a. I and II b. I and III c. II and III d. I, II, and III

a. I and II

Which of the following is a frame of reference for measuring motion? a. coordinate system b. diagram c. graph d. none of the above

a. coordinate system

An action exerted on an object which may change the object's state of rest or motion defines: a. acceleration. b. force. c. mass. d. velocity.

b. force

The gravitational force exerted on an object would most likely be represented by which force vector? a. [up arrow] b. [arrow to the right] c. [down arrow] d. [arrow to the left]

c. [down arrow]

Two books are lying next to each other on a library table. The force due to gravity on the first book is 9 N and on the second is 13 N. The gravitational force on the table itself is 125 N. The floor supports the table with an upward force of 147 N. In a free-body diagram of the table, how many contact forces and how many field forces should be represented? a. 1, 2 b. 1, 3 c. 2, 2 d. 3, 1

d. 3,1

Which of the following statements are true about the concept of field forces? I. Field forces can be exerted by objects that are in physical contact. II. Field forces can be exerted by objects that are not in contact. III. There are four fundamental field forces. a. I only b. II only c. II and III d. I, II, and III

d. I, II, and III

Which of the following statements describe force diagrams? I. Force diagrams show force vectors as arrows. II. Forces exerted on the object are represented. III. Forces exerted by the object are represented. a. I and II b. I and III c. II and III d. I, II, and III

d. I, II, and III