High School physics questions

[Rogan Josh]

A friend of mine is going off to start a career as a High School physics teacher (God knows why). For his application to a private school (which are good in the UK - and much safer than state schools) he has to come up with some final year high school level questions which will made the kids think a little.

He told me two of his questions so far, but I wasn't sure of the level. Since some of you here go to high school, maybe you can let me know if the level is 'right'. Here are the questions:

1. How is the period of a grandfather clock's pendulum affected by putting it on the international space station?

2. Which is stronger: the gravitational attraction of the Earth on the moon or that of the sun on the moon?

Are these too easy, too hard or what?

[woke26]

my guess would be a little too hard. i did college in the netherlands in a scientific study, but i cant answer these 2 with certainty.

[Dauphin]

2 is easy. Just use common sense. You don't even need numbers.

[Berzerker]

1) Period being the time it takes for the weight to make a swing and back? I have to ask, it's been awhile. Assuming it's not a mechanically driven pendulum, I'd say the period would be shortened.

2) The second, I'd have to calculate the distances and gravitational pulls of the objects, but I'm not into it right now (or ever ).

To answer your question, those questions are easy if the subject matter was taught during the year. If it wasn't, they still aren't that good for your/his stated purpose. They reflect more memory than intelligence. If your friend requires the students to work out the math for those questions, that would show they can handle the material instead of just memorising a yes or no answer (this would be ridiculously hard if the material wasn't covered though).

[Rogan Josh]

Originally posted by Big Crunch
2 is easy. Just use common sense. You don't even need numbers.

Which was why I didn't give any.

[Berzerker]

2 is easy. Just use common sense. You don't even need numbers.

What is it, and why?

[Eli]

1) Wont it go in circles?

[Berzerker]

It's a grandfather clock.

[Eli]

But the pendulum is what's important. I assumed that the clock itself is immaterial.

[Berzerker]

To make the question logical, the clock part would have to be removed. That's why I concluded a period was just one swing since it can't make a circle as part of a clock.

[dannubis]

answer to question 2 : they both pull at each other with the same force. it is only because the mass of the moon is much smaller of that of the earth that the moon gets the much bigger acceleration...

even you attract the earth with the same force as the earth attracts you ...

[Eli]

Then what are we arguing?

[Dauphin]

Originally posted by dannubis
answer to question 2 : they both pull at each other with the same force. it is only because the mass of the moon is much smaller of that of the earth that the moon gets the much bigger acceleration...

even you attract the earth with the same force as the earth attracts you ...

I think you misunderstood the question.

[Berzerker]

Then what are we arguing?

I guess the validity of the question. If a period is a circle, then attaching the pendulum to something that doesn't turn and asking for changes in the period wouldn't make sense.

dannubis -

even you attract the earth with the same force as the earth attracts you ...

If you jump in the air, does the earth move in your direction as much as you move toward the earth when landing? If you were right, we'd be floating along the surface waiting to hit a bump and bounce off into space.

[Dauphin]

He is right though, just not answering what the question asked.