posted by mysterychicken .
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!!
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.
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!
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.
So number 4 is actually D
work=force times distance
300 times 100= 30,000
If you are confused on one and you cant find the answer on a website, go into the lesson again or look in your text book if you have one.