Homework Help: Physical Science

Posted by mysterychicken on Sunday, May 3, 2009 at 12:36pm.

These are multiple-choice questions:

1.How much work is accomplished when a force of 300 N pushes a box across the floor for a distance of 100 M?
A- 300 N
B- 30,000 N
C- 300 J
D- 30,000 J
I chose D

2.How do simple machines make work easier?
A- They change the strength or direction of a force
B- They apply force quickly
C- They decrease the power available
D- They maintain the distance of a force
I chose A

3.What has changed when a gardener uses a lever to lift a rock, instead of lifting it by hand?
A- More force is applied over the longer distance
B- Less force is applied over a longer distance
C- More forcec is applied over a shorter distance
D- Less force is applied over a shorter distance
I chose D...?

4.Liz is on a swing. When Liz approaches the highest point, what is true about her potential and kinetic energy?
A- Potential and kinetic energy are equal.
B- Potential and kinetic energy are at zero.
C- Potential energy is at lowest, and kinetic energy is at highest
D- Potential energy is at highest, and kinetic energy is at lowest.
I wasn't sure about this one but I chose C

5.When the temperature of an object increases, what happens to the kinetic energy of the particles in the object?
A- It decreases
B- It increases
C- It is conserved
D- It equals zero
I think it might be A or B...

Thanks so much!!
-MC

Physical Science - drwls, Sunday, May 3, 2009 at 1:12pm
You are correct with 1 and 2. You are wrong with 3 and 4, and should try to give each problem more thought. One of your answers for 5 is right and the other is wrong. You seem to me taking wild guesses instead of thinking about what potential energy and temperatiure really means.
Physical Science - mysterychicken, Sunday, May 3, 2009 at 1:32pm
OK, I've been trying my best and for 3 I got B and for five I got B...? 4 still seems really tricky to me!
-MC
Physical Science - drwls, Sunday, May 3, 2009 at 3:02pm
3B is correct

4. Potential energy increases with height above the ground. At the top of the swing, the velcoity is zero.

5. When heat is added to a mass (and the temperatuire rises), that energy must go somewhere. It goes to make the molecules move faster.
Physical Science - mysterychicken, Sunday, May 3, 2009 at 3:59pm
THANK YOU!!
-MC
Physical Science - mysterychicken, Sunday, May 3, 2009 at 4:10pm
So number 4 is actually D
-MC
Physical Science - drwls, Sunday, May 3, 2009 at 7:20pm
Yes!

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