Link to worksheet: https://docs.google.com/document/d/1ZX4Qi2tVFbF1NTvnDr5Urjb180IdQ6pgjXeablixU_A/edit?usp=sharing

Here is the solution for question two which say that "A 0.200 kg mass on a spring executes simple harmonic motion at a frequency of f. What mass is necessary for the system to vibrate at a frequency of 2f?"

 

Solution: Let f = 1 and solve for K. Then, give f a value of 2 because the frequency double and solve for m using the previously calculated k value. M should be equal to 0.05kg. Try it and I'll break it down some more for you tomorrow. Good luck!

 

Instruction: Conduct research regarding the properties of light and use it to evaluate the claims. Your evidences should be based on known experiments such as photoelectric effect, pair production (particle), reflection, refraction, diffraction, interference (wave).

 

Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model, and that for some situations one model is more useful than the other. [Clarification Statement: Emphasis is on how the experimental evidence supports the claim and how a theory is generally modified in light of new evidence. Examples of a phenomenon could include resonance, interference, diffraction, and photoelectric effect.] [Assessment Boundary: Assessment does not include using quantum theory.] 

 

Elsinore High School

Physics Practice Test : Work, Energy and Power

Teacher: G. Mcbeth

11/28/2918

Instruction: Do all questions.

1.  A 40 - kg man runs at a constant velocity of 3 m/s. What is his kinetic energy?

Ans. ½ mv2  = ½ x 40 x 9 = 180J

2.   A 20 - N force is applied horizontally on a box to move it 5 m across a frictionless surface.

     How much work was done to move the box?

Ans. W = F x d = 20N x 5m = 100J

3.   A constant net force of 250 N moves a 500 - kg car 50 m. If the car was initially at rest,

     then what is the car’s final velocity?

Ans. F = ma , a = F/m = 250N/500kg = 0.5 m/s2

v2 = u2 + 2ad, v = 2 x 0.5 x 50= 7.07m/s

4.   A mover user a pulley system to lift a grand piano with a mass of 250 kg from the ground to

     a height if 5 m.  What is the change in the piano’s gravitational potential energy?

Ans. mgh = 250 x 9.8 x 5 = 12250 J

5.   A boy pulls a 5 - kg box across an ice rink for a distance of 25 m. He exerts a constant force

     of 5 N on a rope attached to the box at an angle of 600. How much work has he done on the

     Box?

Ans. W = 5cos60x 25 = 62.5 J

         

6.  A 2.5 - kg box slides down a frictionless incline from a vertical height of 5 m. The box starts

    from rest. What is the box’s velocity at the bottom of the hill?  

Ans. mgh = ½ mv2 at the bottom

2.5 x 9.8 x 5 = ½ x 2.5 x v2

122.5 = 1.25 v2

v = 122.5/1.25 = 9.90 m/s

7.   An archer pulls her bowstring back a distance of 10 cm with an average force of 35 N. The

     arrow has a mass of 10.0 g. When he releases the string, what is the velocity of the arrow

     when it leaves the bow?

Ans. W = ½ mv2

       35N x 0.1m = 0.5 x v2

v = 3.5/.5 = 2.6 m/s

8.   A 500-kg car traveling at 15 m/s skids 5 m before it stops. What magnitude of the force is

    the frictional force on the car?

Ans. v2 = u2 + 2ad

0 = 152 + 2 x 5 x a

-225/10 = a

a = -22.5 m/s2

F = ma

F = 500 x -22.5 = - 11250 N

10. A 4.5-kg box is attached to a horizontal spring constant of 1,250 N/m. If the box is pulled 6

     cm horizontally from the equilibrium position, what is the maximum kinetic energy?

Ans. ½ k x2 = ½ mv2

.5 x 1,250 x .062 = kinetic energy

= 2.25 J

11. A spring with a constant of 150 N/m is stretched by 0.25 m. What is the force on the spring?

Ans. F = kx

F = 150 x 0.25 = 37.5 N

12. A spring with a constant of 200 N/m is stretched by 0.25 m. What is the elastic potential

     energy stored in the spring?

½ kx2 = .5 x 200 x 0.252 = 6.25 J

13. A 0.5 -kg block is attached to a spring with a constant of 50 N/m. The spring is displaced 0.1

     m from equilibrium. When the block is let go, what is its velocity as it passes the equilibrium

     Point?

Ans. ½ kx2 = ½ mv2

0.5 x 50 x (0.1)2 = 0.5 x 0.5 v2

0.25 = 0.25 v2

v = 1 m/s

14. Two cannons fire identical cannonballs with the same amount of powder. The barrel of

    Cannon 2 is 3 times as long as the barrel of Cannon 1. How does the velocity of a cannonball

    fired from Cannon 2 compared with that of the ball fired from Cannon 1?

15. A 350 -kg glider is flying level at 50.0 m/s. A tailwind blows constantly for 600 m, and

    the glider’s speed increases to 60.0 m/s. What is the approximate force of the tailwind?

Ans. Work = ½ mv2 - ½ mu2 = F x d

F x 600 = ½ x 350 x 602 - ½ x 350 x 502

F x 600 = 630000 - 437500

F x 600 = 192500

F = 192500/600 = 320.8 N

16. The gravitational potential energy of a box sliding down an incline decreases by 12.5 J while

     the kinetic energy increases by 11.5 J. How can you account for the the difference in energy?

Ans. 2J of energy represent heat produced by the box.

17. An object is initially at rest. A force of 1.0 N exerted on an object for 2.5 m increases the

     object’s velocity by .50 m/s. What was the mass of the object?

Ans. v2 = u2 + 2ad

0.52 = 0 + 2 x 2.5 x a

a = 0.104 m/s2

F = ma

m = F/a

m = 1.0/0.104 = 9.62 kg

18.A 35.0 -kg stuntman free falls from a building for 62 m and hits an airbag. The airbag exerts

    a force on him as he depresses it 5.0 m and comes to a complete stop. What is the average

    force exerted by the airbag?

mgh = Work done

mgh = F x d

35.0 x 9.8 x 62 = F x 5.0

F = 4253.2 N

19. A man pushes a 50 -kg box with a horizontal force of 50 N across a floor for a distance of

    30 m in 1 min. What is his power?

Ans. P = W/t

P = 50 x 30 / 60s = 25W

Questions 20 -22 refer to the figure below. For each question, assume that the roller coaster was initially moving to the right as it approaches point A. Also assume air drag and tract friction are negligible.

20.The diagram above depicts a frictionless roller coaster tract with various locations labeled

    A through E. At which locations will a roller coaster car have the same gravitational

    potential energy?

21. At which location will the roller - coaster car move the fastest?

22. For this diagram, at which point will the total energy be the greatest?

23. A man pushes a lawn mower with a handle at an angle of 300 to the horizontal. He applies a

     constant 10 - N force along the axis of the handle and moves the lawn mower a horizontal

     distance of 50 m in 2.5 min. What is the man’s power output?

Ans. P = W/t = 10cos30x 50/ 150s = 433.01/150 = 2.89 W

24. A 1,000. 0 -kg airplane flies at 172 m/s. What is its kinetic energy?

Ans. KE = ½ x 1,000 x 1722 = 14792000J

25. A rifle fires a 2.0 -g bullet at a velocity of 425 m/s. If the length of the rifle barrel is 0.51 m,

    then what force does the riffle exert on the bullet?

Ans. KE = Work done

½ x 0.002 x 4252 = F x 0.51

180.625 = F x 0.51

F = 354.17N

Sorry for the lateness. I has an emergency.

Honors Physics: I have a copy of the SOLAR CUP  Electrical Report that I want you to modify and refine it. We really need to start working on it as quickly as possible. Cameron your computer skill would be quite valuable. Please pick up a copy after school so that you can start working on it right away. Thanks much! I strongly believe in you all!

Please bring your materials for the torque lab. We are going to finish up that lab on Tuesday. Also, Tuesday is the deadline for the homework assignment.

Remember to turn in your labs on Tuesday!