# What do i need to learn in order to do the following contest questions?

1. Nov 27, 2004

### furtivefelon

hi, here is several contest problems from my school's physics team.. i just joined, but it's for grade 12 ppl, i'm only in grade 11, so i'm trying to find out what i need to learn in order to do these questions.. just put some general topics, such as "simple machines.." but if you want to be specific, it's more than welcome! :D

anyhow, here is the problems:

problem 1. Two little balls with masses m1 and m2 are connected with a spring and lie on the smooth horizontal surface. The spring constant is k. The balls are brought close to each other, and the spring becomes compressed. Then they are simultaneously released. Determine teh period of the resultant oscillations of two balls.
The period of oscillations of a point mass on a spring is given by:
T=2pie sqr m/k

problem 2. A rope is thrown over a puilly with its one part on the table of height h, and its another part on the floor. After the rope is releaesd it starts to move. Find the speed of the steady motion of the rope.

problem 3. At the height of 200km the density of the Earth's atmosphere is 1.6*10^-10 km/m^3. A satellite has a mass of 10kb and a cross sectioal area of 0.5 m^2.
Estimate the resistance force experienced by the satellite at this altitude.

problem 4. Two identical little balls are connected with a string. One of them is thrown up with a initial speed v.
What is the maimum altitude of the system?

problem 5. propose an experiment to determine the acceleration due to gravity and perform it witht he obligatory use of the following equipment: ramp, tape measure, timer, and a roll of a bathroom tissue. Any other facilities can also be added if necessary.
your result must contain the explanation and diagram of the experiment, the value of the obtained acceleration g, the value of the error.
For the hollow cylinder, moment of inertia about the principal axis of rotation equals I = (M(R1^2 + R2^2))/2, where M is it's mass, and R1 and R2 are hte internal and the expernal radii..

thanks alot for helping me :D

2. Nov 27, 2004

### ponjavic

for 1, haven't really thought about it but it looks like a linear momentum problem
for 2, didn't understand this one
for 4, i think basic distans/velocity/accelleration would do, not sure though
for 5, energy conservation of both translational and rotational energy, fricition work loss possibly

3. Nov 27, 2004

### futb0l

problem 1: simple harmonic oscillation and springs...
problem 2: not sure... it should be just Newton's 2nd Law
problem 3: Newton's Law of Universal Gravitation - I think
problem 4: Newton's 2nd Law, I think it requires Work Energy theorem...

4. Nov 27, 2004

### prasanna

For the fifth problem you need to study rotational motion.
in particular moments of inertia of different objects through different axes
and also time taken for differenr objects to roll down an inclined plane.
well, in india, we are taught all the subjects required for your problem in grade 11!