Energy and Work Physics questions(9 multiple choice, 1 open response--Do not have to answer all) ?

Hey Y!A, I was wondering if you could answer the following 10 problems. Also feel free to answer what you know, you don’t have to answer all of them thanks =).

DO NOT HAVE TO SHOW WORK from #’s 1-9, but for 10 show all work possible for every part seperatly.

#1-#9 Just multiple choice, don’t have to show work if you do not want….if you do that would be wonderful though….

1.What is the work done by friction on a15 kg object pulled horizontally in a straight line for 15 meters, if the coefficient of friction between the object and the surface is given by u (moue) k =0.4 (moue kinetic)?

a. –59 J

b. –91 J

c. –145 J

d. –590 J

e. –890 J

2.How much work must be done on a 27.5 kg object to move it 18 m up a 30-degree incline?

a. =4800 J

b. –2400 J

c. 0J

d. 2400 J

e. 4800 J

3.What is the work done to slow a 1.8*10^6 kg train from 60 m/s to 20 m/s?

a. 2.9 * 10^6 J

b. 6.1 * 10^4 J

c. 3.1 * 10^1 J

d. –1.3 * 10^3 J

e. –2.9 * 10^8 J

4. A 45 kg object slides down an uneven frictionless incline from rest without rotating. What is its speed after it travels 2.5 meters vertically?

a. 3.0 m/s

b. 4.3 m/s

c. 5.7 m/s

d. 7.0 m/s

e. 11 m/s

5.Which of the following are equivalent units for the spring constant, k?

I. N * m^2

II. Kg/s^2

III. J/m^2

a. I only

b. II only

c. III only

d. I and II only

e. II and III only

6.For an object sliding down a frictionless uneven incline without rolling, wich of the following represents the change in height necessary for its velocity to double in terms of its initial velocity V?

a. 2 (V^2)g

b. 3V/g^2

c. 3(V^2)/2g

d. 3V/2g

e. 2g/3V^2

7. A 2.0 kg ball compresses a spring 0.10 meters and is released from rest. If the ball leaves the spring at a speed of 0.20 m/s, what is the value of the spring constant?

a. 5.0 N/m

b. 8.0 N/m

c. 12 N/m

d. 16.0 N/m

e. 18.0 N/m

8.What is the force of friction as a 12 kg object slides for 30 meters down a 30 degree incline at a constant velocity?

a. 59 N

b. 98 N

c. 280 N

d. 540 N

e. 1100 N

9.What is the average power necessary to move a 35 kg block up a frictionless 30 degree incline at 5 m/s?

a. 68 W

b. 121 W

c. 343 W

d. 430 W

e. 860 W

Open response; please show all work for all parts, thanks.

10. A 6 kg ball is pressed against a spring with a k value of 23 N/m , compressing it by 0.5m. The spring is horizontally with a ledge. The length of the spring in its resting position equals the length of the ledge. The ledge is 15 m above the ground.

a. What is the elastic potential energy initially?

b. What is the gravitational potential energy when the ball leaves the spring?

c. What is the gravitational potential energy when the ball hits the ground?

d. Find the magnitude of the velocity vector when the ball hits the ground.

e. How far from the base of the ledge will the ball land

Thanks for answering, and please only answers relevant to answering the question,

Classicgirl