# Physics midterm exam | Physics homework help

## Physics Midterm Exam

**Directions:** It is important that you provide answers in your own words. Please focus only on information from the text/eBook to create your own solutions. Please do not use direct information from an outside source (especially copying and pasting from an “answer” website). Use of direct information from an outside source is against school policy. *All answers will be checked for plagiarism. Instances of plagiarism* *can result in probation or possible dismissal from the school. *

*Grading:** Please be sure to follow all guidelines (number of sentences/showing all calculations) and to provide the correct metric units of measure. All questions are 3.33 points (.33 for units). You MUST include units on all your answers. *

For any math based questions you must show all your work and explain any numbers that are not clearly understood by the problem.

#### 1. Use at least two to three completed content related sentences to explain why physics is considered the basic science. Provide at least one example to explain how physics relates to other sciences.

2. You do work on something when you lift if against gravity. Explain how work relates to gravitational potential energy using at least two complete content related sentences. If the lifted object is released, describe the change in energy. Be sure to define all terms used in both questions.

3. In terms of momentum change, explain why it is best to “give” when catching a baseball. Provide at least TWO other examples of situations in which you want “give”.

4. A boy fires a table tennis launcher. Briefly describe the forces and impulses on the launcher and the ball. Explain which has momentum. Explain which is moving faster. Be sure to use at least 3 to 4 complete content related sentences.

5. Write 4 to 5 sentences about what Chapter 1 says about the early scientists from Aristotle to Galileo thought about the nature of motion. (Hint: Need to include Aristotle, Galileo, and Copernicus.

6. Suppose you are on an airplane moving at high speed. If you flip a coin straight up it will land in your lap rather than a great distance behind you. Explain why this is true and include any laws that help prove your point. Your answer should be at least 3 to 4 complete content related sentences.

7. What is terminal speed? When a skydiver has reached terminal speed, what is the are resistance equal to? What is the skydiver’s acceleration? Be sure to use at least 3 to 4 complete content related sentences.

8. A force is a push or a pull. Newton’s third law further defines the meaning of force. Be sure to explain using at least 3 to 4 complete content related sentences.

9. The sun radiates about 3.6 x 10^{26} joules of energy each second. How much mass does the lose each second? Show all of your work and be sure all numbers must be clearing identified and explain in your work.

10. Provide the time dilation equation found in Section 15.4 of the text. Explain each step of the derivation.

11. You sit at the outer rim of a Ferris Wheel that rotates 2 revolutions per minute (RPM). What would your rotational speed be if you were instead clinging to a position halfway from the center to the outer rim. Be sure to provide at least 3 to 4 complete content related sentences and show any work needed to support your answer.

12. At the outer edge of a rotating space habitat, 130 m from the center, the rotational acceleration is g. What is the rotational acceleration at a distance of 65 m from the center of the habitat? Be sure to show all work and steps to support your answer.

13. A car traveling at 60 km/h will skid 30 m when its brakes are locked. If the same care is traveling at 180 km/h, what will be the skidding distance? Be sure to show all work to support your answer.

14. At what height does a 1000-kg mass have a potential energy of 1J relative to the ground? Be sure to show all work to support your answer.

15. A bicycle travels 15 km in 30 minutes. What is its average speed? Be sure to show all work to support your answer.

16. What is the average acceleration of a car that goes from rest to 60 km/h in 8 seconds? Be sure to show all work to support your answer.

17. What speed must you toss a ball straight up so it takes 4 s to return to you? Be sure to show all work to support your answer.

18. Assume that a 15-kg ball moving at 8 m/s strikes a wall perpendicularly and rebounds elastically at the same speed. What is the amount of impulse given to the wall? Be sure to show all work to support your answer.

19. A net force of 1.0N acts on a 4.0-kg object, initially at rest, for 4.0 seconds. What is the distance the object moves during the same time? Be sure to show all work to support your answer.

20. What is the energy equivalent of 5.0 kg of mass? Be sure to show all work to support your answer.

21. A sky diver steps from a high-flying helicopter. If there were not air resistance, how fast would she be falling at the end of a 12 second jump?

22. Kerry Klutz drops her physics book off her aunt’s high rise balcony. It hits the ground below 1.5 s later.

a. With what speed does it hit?

b. How high is the balcony (ignore air drag).

23. Mark accidentally falls out of a helicopter that is traveling 15 m/s. He plunges into a swimming pool 2 seconds later. Assuming no air resistance, what was the horizontal distance between Mark and the swimming pool when he fell from the helicopter?

24. Consider the two forces acting on a person who stand still, namely, the downward pull of gravity and the upward support of the floor. Are these forces equal and opposite? Do they comprise an action-reaction pair? Why or why not?

25. If a car traveling at 60 km/h will skid 20 m when its brakes lock, how far will it skid if it traveling at 120 km/h when its brakes lock?

26. Stand with your heels and back to the wall and lean over and touch your toes…. What happens??? Yep, you topple. Which would help you in completing this task, stronger legs or longer feet. Use 2 to 3 complete content related sentences to defend you answer.

27. Alec says the force of gravity is stronger on a piece of paper after it’s crumpled. His classmate, Jordan, disagrees. Alec “proves” his point by dropping two pieces of paper, one crumpled and the other not. Sure enough, the crumpled piece falls faster. Has Alec proven his point? Use at least 2 to 3 complete content related sentences to explain.

28. Calculate the speed in m/s at which the moon revolves around the Earth. Note: the orbit is nearly circular.

29. Using at least 3 to 4 complete content related sentences describe the first and second postulate of special relativity.

30. You are playing catch with a friend in a moving train. When you toss the ball in the direction the train is moving, how does the speed of the ball appear to an observer standing at rest outside the train? Be sure to use at least 3 complete content related sentences to explain.

Formula Sheet

The following formula are the base formula and may be used in it base state or may need to be manipulated to fit the question.

E=mc^{2}

F=ma

d=1/2at^{2}

mV = Mv

V=gt

S=d/t

1J = m x 9.8 x h

W = ΔKE

F_{c} = mv^{2}/r

d = ½ gt^{2}

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