Physics 213 Test 1 10 points each Oct. 1, 1997

1. a)What is the value of the ratio of circumference to diameter of any circle ?

b) Write down the meaning of this value.

c) If the circumference of a circle is increased by 8.39¹ cm , by how much is the diameter increased?

2. Suppose for each elephant there are 10 mice. Use L to represent the number of elephants and M to represent the number of mice, and:

a) Write down the ratio that equals 10_______________

b) Write down the ratio that equals 1/10_____________

c) Express M as a function of L and L as a function of M

3. Instructions : Write an equation of the dependent variable (vertical axis) as a function of the independent variable (horizontal axis) for the graph on the right.

Describe in complete sentences the situation being illustrated by the graph.

4. A concrete block of the shape shown hangs from a thin metal strip having the cross-sectional shape indicated in the inset on the left of the diagram. Suppose the block is increased in size through scaling up each of its three linear dimensions by a factor of 2.10 without change in the material of which it is composed.

(a) By what factor will the weight of the block be increased because of the change in dimensions? (Calculate the numerical value and explain your reasoning briefly.)

(b) By what scale factor must the linear dimensions of the cross section of the suspending strip be changed to compensate for the change in weight of the block, making sure that the strip does not break? Explain your reasoning briefly. (Remember that the breaking strength of the strip is proportional to its cross-sectional area, not its volume.)

5. Below is the motion diagrams for two different objects C and D. Clock readings are indicated in the boxes.

a) Do both have uniform velocity?

b) Which is travelling fastest to begin with?

c) Which travels for the greatest length of time?

d) Which travels the greatest distance ?

e) At which clock readings(instants) do they occupy the same location at the same time?

f) Is there any time interval over which they have the same average velocity?

g) Are they ever travelling the same speed at any clock reading?

h) Which would accurately indicate the speed of the object at clock reading 2, an arrow drawn from 2 to 3 for C or an arrow drawn from 2 to 3 for D?

6. Describe the motion required to create a U-shaped graph .

7. Sketch the distance vs time curve for this motion. The object moves away from the origin, starting slowly and speeding up.

8. Describe the motion indicated in the figure below.

9. How can one move a distance of 4 meters and have a net displacement of 3 m ?

10. A skier was seen to have velocities of 10 mi / hr, 25 mi hr , 40 mi / hr, and 55 mi / hr at t = I s, 2 s , 3s , 4 s, 5 s, etc.

Is her acceleration constant? If so, what is it ?

11. As the ball rolls down this hill: (Circle the appropriate response)

a. its speed increases and acceleration decreases

b. its speed decreases and acceleration increasesc

c. both increase

d. both remain constant

e. both decrease

12. The velocity-time graph of an object is shown below. Figure out the total distance traveled by the object. Show your work.