Physics 1303/1403 Professor Olness

EXAM 1 September 21, 1999

1) (20 Points) Professor Einstein takes a trip. The first leg of his journey, he travels: A is15km 30 degrees West of North; B is 10km 60 degrees West of South, C is 5km 45 degrees South-East, Find the components of the total displacement vector D. Find the magnitude of the total displacement vectorD. Find the angle of D in degrees. Sketch the total trip on the plot.

2) (20 Points) Troy's sister throws a football at a velocity of 60m/s at an angle of 20 degrees from a cliff that is 400m high. a) Find the time the ball is in the air. b) (5 Points) Find the total horizontal distance covered. c) (5 Points) Find maximum vertical height above the cliff.

3) (20 Points) You are given the information listed in the table and on the plots. Your mission is to fill in the empty entries, and plot each quantity.
(Be sure and label the graphs so I can see real numbers. Each grid unit need not be 1 unit.)

4a) (12 Points) Fill in the following table. C= A-B. (Warning, this is subtraction!!!)

A_X= A_y= |A|= q_A=

B_X= B_y= |B|= q_B=

C_X= C_y= |C|= q_C=

4b) (8 Points) In Dallas, the speed of the rotating earth is approximately 700 miles per hour, or approximately 350m/s. The radius of the earth is R_E=6,400Km.

· Compute the radial acceleration in MKS units

· Compare this with "g." That is, compute a/g

5) (20Points) A soda jerk slides a root beer float down the counter, but misses the customer.
The float slides off the end of the horizontal counter (height 1meter), and hits the floor a horizontal distance of 4 meters from the edge of the counter.

a) (10Points) What was the speed of the float when it left the counter.

b) (10Points) What is the velocity of the float just before it hits the floor.

(I want a magnitude and direction (angle) of the velocity vector.)

6) (20Points) True or False? Circle the correct answer. (2 points each).

1) A and B have different dimensions. The following quantity IS physically meaningful? A+B

2) A and B have different dimensions. The following quantity IS physically meaningful? A/B

3) A and B have different dimensions. The following quantity IS physically meaningful? B-A

4) A and B have different dimensions. The following quantity IS physically meaningful? AB

It is possible to use {length, density, time} as fundamental units instead of {length, mass, time}.

6) Average velocity and instantaneous velocity are always the same value.

7) If the acceleration is zero, the velocity must be zero.

8) If the acceleration is constant, the velocity must be zero.

9) If the velocity is zero, the acceleration must be zero.

10) If the velocity is positive, the acceleration must be positive.