Week 1 Practice Problems

Week 1 Practice Problems

These problems are meant to give you more practice on the concepts covered during the first week of class. You are not required to do any of these, they are purely for your benefit. If you have any questions about any of these feel free to email me or come see me! Some of these are taken from past exams, so it should be good practice for our exam.

1. While I am riding on a plastic horse on a merry-go-round, which statement is true about my acceleration and velocity vectors?

a) They are both pointing in the same direction.

b) They are perpendicular to each other.

c) They are anti-parallel (parallel but pointing opposite directions).

d) Their directions depend on the rate of rotation of the merry-go-round.

2. You shoot an arrow in a high arc toward a target located some distance away. At the highest point of the flight, which statement best describes the motion of the arrow?

a) The velocity and acceleration are both nonzero.

b) The velocity is zero and acceleration is nonzero.

c) The velocity is nonzero and acceleration is zero.

d) The velocity and acceleration are both zero.

e) Insufficient information is given to answer.

3. During an Olympic bobsled run, the Jamaican team makes a turn of radius 7.6 meters at a constant speed of 96.6 kilometers per hour. What was the magnitude of their acceleration during this turn? Express as a multiple of g.

4. You are all geared up for a walk. You know you have enough chocolate milk in your CamelPak to take go 120m but after that, you’ll probably need to stop for a well-deserved ice cream treat and then head out for another 130m. Describe how you can walk in order to make the resultant displacement of your trip

1. 250m
2. 10m
3. 50m

5. Let a = 3 î + 4 ĵ and b = 15î + 26 ĵ. Find a+b and a-b. Specify your answers in two ways: first by giving the component form of the resulting vector and second by giving the magnitude and direction (angle).

6. A train started from rest and moved with constant acceleration. At one time it was traveling at 30 m/s and 160m farther on it was traveling at 50 m/s. Calculate

a.  the acceleration (assume it is constant!)

b.  the time required to travel the 160m

c.  the time required to attain the speed of 30m/s

d.  the distance the train moved from its starting point at rest to the speed of 30m/s

7. A driver’s manual handbook states that an automobile with good brakes and going 50 mi/hr can stop in a distance of 186 ft. The corresponding distance for 30 mi/hr is 80 ft. Assume that the driver reaction time, during which the acceleration is zero, and the acceleration after the brakes are applied are both the same for the two speeds. Calculate

a.  the driver reaction time

b.  the acceleration (in mi/hr2 )

8. A ball is thrown vertically downward with an initial speed of 20.5 m/s from a height of 58.8m.

a.  What will be its speed just before it strikes the ground.

b.  How long will it take for the ball to reach the ground?

c.  What would be the answers to (a) and (b) if the ball were thrown directly up from the same height with the same initial speed?

9. A dive bomber, diving at an angle of 56.0 degrees with the vertical, releases a bomb at an altitude of 730 m. the bomb hits the ground 5.10 s later, missing the target.

a.  What is the speed of the bomber?

b.  How far did the bomb travel horizontally during its flight?

c.  What were the horizontal and vertical components of its velocity just before striking the ground?

d.  At what speed and angle with the vertical did the bomb strike the ground?

10. A football is kicked off with an initial speed of 64 ft/s at a projection angle of 42 degrees above the horizontal. A receiver on the goal line 65 yd away in the direction of the kick starts running to meet the ball at that instant. What must be his average speed if he is to catch the ball just before it hits the ground? Neglect air resistance.