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Can you check my answers? Physical Science?

Discuss anything to do with property law - buying, selling property

Can you check my answers? Physical Science?

Postby freedom97 » Tue Mar 13, 2012 9:48 am

1. If you perform 10 joules of work lifting a 10-N box from the floor to a shelf, how high is the shelf? (1 point)
1 m<-------This one
2 m
10 m
100 m

2. How can a machine make work easier for you?
(1 point)
by decreasing the amount of work you do
by changing the direction of your force <------
by increasing the work done by the machine
none of the above

3. How can you make the work output of a machine greater than the work input? (1 point)by decreasing friction
by increasing the input force
by increasing the output distance
none of the above <------- This one

4. Reducing friction in a machine
(1 point)
decreases its actual mechanical advantage.
decreases the work output.
increases its efficiency. <------This one
increases its ideal mechanical advantage.


5. The ideal mechanical advantage of a pulley system is equal to the
(1 point)
distance the load has to move.
length of the rope.
number of rope segments supporting the load.
weight of the object being lifted. <------This one

6. A machine is classified as a compound machine if it
(1 point)
has moving parts.
has an IMA greater than 1.
is made up of two or more simple machines that operate together. <------
is very efficient.

7. What is transferred by a force moving an object through a distance?
(1 point)
force
mass
motion
energy <-------

8. A 10-kilogram bicycle is traveling at a speed of 2 m/s. What is the bike’s kinetic energy? (1 point)10 J
20 J <-------
2 J
200 J

9. A 4-kilogram cat is resting on top of a bookshelf that is 3 meters high. What is the cat’s gravitational potential energy relative to the floor if the acceleration due to gravity is 9.8 m/s2?
(1 point
7 J
12 J
29 J
118 J <------This one

10. Nuclear power plants are designed to convert nuclear energy into what type of energy? (1 point)chemical
electrical <------This one
geothermal
mechanical

11. Which of the following statements is a consequence of the equation E = mc2?
(1 point)
Energy is released when matter is destroyed.
Mass and energy are equivalent.
The law of conservation of energy must be modified to state that mass and energy are conserved in any process.
all of the above <------This one


Figure 15-1

12. The kinetic energy of the pendulum bob in Figure 15-1 increases the most between locations (1 point)
A and B.
A and C. <--------
B and D.
C and D.

13. What property of an object is related to the average kinetic energy of the particles in that object?
(1 point)
specific heat
mass
conductivity
temperature <------This one

14. Thermal energy depends on an object’s
(1 point)
mass.
phase (sold, liquid, or gas). <---This one
temperature.
all of the above

15. How do you know that a sealed calorimeter is a closed system?
(1 point)
because temperature is conserved
because the masses of the sample and water are equal
because thermal energy is not transferred to the environment <----This one
because work is done on the test sample


16. The vacuum inside the thermos bottle shown in Figure 16-1 stops which type of thermal energy transfer to keep the liquid hot?
(1 point)
convection
conduction
radiation
both a and b <---- This one

17. To which of the following does the first law of thermodynamics apply?
(1 point)
heating objects
transferring thermal energy
doing work on a system
all of the above <----This one

18. The second law of thermodynamics states that thermal energy can flow from colder objects to hotter objects
(1 point)
by convection.
only if work is done on the system. <----this one
spontaneously.
when thermal expansion takes place.

19. One consequence of the third law of thermodynamics is that
(1 point)
heat engines have efficiencies less than 100 percent
in some energy conversions, energy is not conserved
engines cannot discharge waste heat
the work a heat engine produces is less than the waste heat it produces <----This one

Fill in the Blank

20. A machine is a device that changes a(an) ____________________.
(1 point)

21. Besides a reduction in friction, the only way to increase the amount of work output of a machine is to ____________________ the work input.
(1 point)

22. The mechanical efficiency of any machine is always ____________________ than 100 percent.
(1 point)

23. When a pole vaulter flexes the pole, the pole vaulter increases the pole’s ____________________ potential energy.
(1 point)

24. Wind turbines convert ____________________ energy into electrical energy.
(1 point)

25. Energy resources that exist in limited amounts and, once used, cannot be replaced except over the course of millions of years are called ____________________ energy resources.
(1 point)

26. The increase in volume of a material due to a temperature increase is called _________________________.
(1 p
freedom97
 
Posts: 26
Joined: Thu Mar 31, 2011 6:47 am

Can you check my answers? Physical Science?

Postby link » Tue Mar 13, 2012 9:51 am

5 - number of segments of rope supporting the load (remember, greater mechanical advantage for a pulley is gained with more supporting ropes at a cost of distance of rope and friction)

12 - can't see figure

14 - all of the above, thermal energy is the totality of mass, phase, and temperature. A glacier has more thermal energy than a hot potato. The hot potato while higher in temperature cannot melt much of the glacier.

20 - direction or magnitude of a force

21 - increase

22 - less

23 - elastic

24 - kinetic

25 - nonrenewable, finite

26 - thermal expansion
link
 
Posts: 19
Joined: Fri Apr 01, 2011 11:35 pm

Can you check my answers? Physical Science?

Postby darrell » Tue Mar 13, 2012 9:53 am

5 - number of segments of rope supporting the load (remember, greater mechanical advantage for a pulley is gained with more supporting ropes at a cost of distance of rope and friction)

12 - can't see figure

14 - all of the above, thermal energy is the totality of mass, phase, and temperature. A glacier has more thermal energy than a hot potato. The hot potato while higher in temperature cannot melt much of the glacier.

20 - direction or magnitude of a force

21 - increase

22 - less

23 - elastic

24 - kinetic

25 - nonrenewable, finite

26 - thermal expansion
darrell
 
Posts: 22
Joined: Fri Apr 01, 2011 2:44 pm


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