Phys 110 Principles of Physics Test 1 February 7, 2007 Name ...

Phys 110 Principles of PhysicsTest 1 February 7, 2007Name ________________________Explain as completely as possible! Use complete sentences! Begin with the original equation andshow all work! All numbered questions are worth 10 points each.v avg∆x=∆tg = 9.8 m/s 2∆x = v t +o12at2rrr ∆va = v vo att= +r Fa =m1. a) What are the basic units (in the SI System) of length, mass and time?b) What are the properties of a good standard for a unit? Use the standard for one particular unit toillustrate the properties.2. a) Is it possible to have a velocity toward the south and at the same time an acceleration toward thenorth? Explain, and if it is possible, give an example.b) Is it possible to have zero velocity while having an acceleration that is not zero? Explain, and if it ispossible, give an example.

3. For the position-time graph on the left and the velocity-time graph on the right (each showingdifferent motions), answer the following, with brief explanations. (You should label sections of thegraphs a, b, c, or d, corresponding to the answer to each question.)VelocityPositionTimeTimea) Where is the object moving fastest?PositionGraphb) Where is the object moving slowest?PositionGraph:c) Is the object stopped? Where?PositionGraph:d) Is the object accelerating? Where?PositionGraph:VelocityGraphVelocityGraph:VelocityGraph:VelocityGraph:4. A 10,000 kg rocket in deep space, far away from any air or gravity, moves at a speed of 500 m/s. Howmuch force is required to keep it moving at that same speed? Explain.5. If a large semi-truck and a small Geo Metro have a head-on collision, which vehicle experiences themost force? Which experiences the most acceleration? Explain.

6. a) If a rock is dropped from a point at the same instant that a second rock is thrown horizontally fromthe same point, which one will hit the ground first? Explain why.20 o aboveHorizontal20 o belowb) If the second rock is thrown upward at an angle of 20 o above thehorizontal, now which one will hit the ground first? Explain.c) If the second rock is thrown downward at an angle of 20 o below the horizontal, now which one will hitthe ground first? Explain.7. A person traveled 310 miles in 1.5 months. (1 mile = 1.602 km, and 1 month = 30 days.)a) How far did the person travel in meters?b) What was the person’s average speed in meters per second?

8. A car initially moving at 35 m/s slows down with an acceleration of 2.5 m/s 2 .a) How long does it take the car to come to a stop?b) How far does the car travel in that time?9. A baseball pitcher throws a baseball from the pitcher’s mound to home base, a distance of 18.45 m(60’ 6”). If he throws the ball so that it is initially moving horizontally at 46 m/s, and it leaves his hand at1.8 m above the ground,a) How long does it take to get to the catcher?b) How far has it dropped by the time it reaches the catcher?

10. A 2.8 kg block is acted on by five forces as shown:a) What is the net force on the box? (Give its size and direction.)b) What is the acceleration of the box?15 N8 N12 N14 N15 NExtra Credit: Use the concepts from this unit to explain why a thin stream of water falling from a faucetalways breaks into droplets eventually (rather than staying together as a stream).