PRELIM EXAM PHYSICS FOR ENGINEERS

1. Compute your average velocity in the following two cases:

(a) You walk 73.2 m at a speed of 1.22 m/s and then run 73.2 m at a speed of 3.05 m/s along a straight track.

• 1.74 m/s

• 1.47 m/s

• 2.47 m/s

• 2.14 m/s

1. Compute your average velocity in the following two cases:

(b) You walk for 1.00 min at a speed of 1.22 m/s and then run for 1.00 min at 3.05 m/s along a straight track.

• 1.74 m/s

• 1.47 m/s

• 2.14 m/s

• 2.74 m/s

2.      An automobile travels on a straight road for 40 km at 30 km/h. It then continues in the same direction for another 40 km at 60 km/h.

(a) What is the average velocity of the car during the full 80 km trip? (Assume that it moves in the positive x direction.)

• 40 km/h, (+) x-direction

• 40 km/h, (-) x -direction

• 50 km/h, (+) x-direction

• 50 km/h, (-) x-direction

2.      An automobile travels on a straight road for 40 km at 30 km/h. It then continues in the same direction for another 40 km at 60 km/h.

(b) What is the average speed?

• 40 km/h, (+) x-direction

• 40 km/h

• 50 km/h, (+) x-direction

• 50 km/h

3. Two trains, each having a speed of 30 km/h, are headed at each other on the same straight track. A bird that can fly 60 km/h flies off the front of one train when they are 60 km apart and heads directly for the other train. On reaching the other train, the (crazy) bird flies directly back to the first train, and so forth. What is the total distance the bird travels before the trains collide?

• 60 kms

• 50 kms

• 40 kms

• 30 kms

4. (a) If a particle’s position is given by x = 4-12t+3t^2 (where t is in seconds and x is in meters), what is its velocity at t=1s?

• (+) 6 m/s

• (-) 6 m/s

• (+) 10 m/s

• (-) 10 m/s

4.  (b) What is its speed just then?

• 6 m/s

• 10 m/s

• 20 m/s

• 12 m/s

The position of a particle moving along an x-axis is given by x=12t^2 - 2t^3, where x is in meters and t is in seconds.

Determine (a) the position

• 54 m

• 45 m

• 64 m

• 46 m

5. The position of a particle moving along an x-axis is given by x=12t^2 - 2t^3, where x is in meters and t is in seconds.

Determine (b) the velocity

• (+) 18 m/s

• (+) 20 m/s

• (+) 22 m/s

• (+) 24 m/s

5. The position of a particle moving along an x-axis is given by x=12t^2 - 2t^3, where x is in meters and t is in seconds.

Determine (c) the acceleration of the particle at t = 3.0 s.

• (-) 12 m/s2

• (+) 12 m/s2

• (-) 18 m/s2

• (+) 18 m/s2