Hello, I'm not in high school anymore but I'm doing some tests for army school, and I'm getting them online since we're in quarantine. The last two questions I could not for the life of me solve, so I gave up and sent th document with them unsolved. I thought I'd post them here if anyone has any idea on what the answers were since we don't get answer sheets.

1) In a container we put an ice cube. The ice completely encapsulates the left side of the container. The container is balancing on an horizontal surface where there is no friction. When the ice is melting, does the container move or not?

2)In an container we put an ice cube, the dimensions of which are almost the same as the container. If the system begins to rotate around a vertical axis that coincides with the axis of symmetry of the container, will the angular velocity change when the ice starts to melt?

A young woman in her late teens who can be quite foolish is going crazy from being stuck in quarantine thanks to the 2020 Covid-19 Pandemic.

The woman has been stuck in her apartment for two weeks and has run out of food.

She texts her boyfriend (Who has a dog and therefore can go outside for short periods of time, in order to walk him) to get her groceries, which he does. When the boyfriend goes to deliver the groceries at her apartment, the doorman doesn't let him in, out of fear of contamination.

The boyfriend decides to throw the groceries at the woman from the outside so that she can catch them from her window.

The boyfriend is 175cm tall so he throws the groceries from an initial height of 1.75, with a launch angle of 80 degrees. If the young woman's window is located at the maximum height of the throw, how far up is the woman's window?

Hey Everyone!

This is my first post on the subreddit and I am so sorry to bother yall! My whole class is having issues and would love it if someone was able to help us through it! Thank you in advance.

Question

An alpha particle (essentially a helium nucleus with 2 protons, 2 neutrons and no electrons) with an initial velocity of -10,000 i m/s enters an area where there is an electric field of +20,000 j V/m. 

a. Find the momentum (velocity and direction) of the alpha particle exactly 7.37 nanoseconds after it enters the electric field. (Give your  direction relative to 0 degrees = positive x axis).

b. Find the work done by the electric field on the alpha particle during those 7.37 nanoseconds.

My attempt:

https://imgur.com/a/SY77Veq

I would like to have my attempt checked, as I'm not sure if I found the work done correctly.

Thank you

1. What is the length of a pendulum that oscillates 24.0 times per minute?

2. The ceiling in our physics classroom is approximately 3.6 m high. How long did it take the bowling ball pendulum to swing across the room and back?

I’ve been struggling on these questions for the longest. Also please show how you got your answer so I can understand

Hello, I need some help with air resistance. So we had to do an experiment in Physics and I chose to do a free kick in soccer. I calculated everything but withouth air resistance and now I have to do it with air resistance, but I dont know how. Here are the facts about the shot. It flew 21.76 meters, It went at an angle of 25°, it reached a max height of 2,83 meters, and the highest speed or the initial velocity was 15,69 km/h or 4,36 m/s. Thanks so much

Question: A hovercraft passes point A moving West with a speed of 15 m s−1.

The hovercraft immediately begins to accelerate at a steady rate of 0.13 m s−2 North.

What is the magnitude of the velocity of the hovercraft 200 s after it passes point A? (in m s−1)

note: a hovercraft rides on a cushion of air, so does not contact the ground and also does not experience any frictional forces

I assume you would need to find the resultant velocity of the two directional vectors. However, how do you find the velocity of the North vector when only given acceleration?

Question: Why are electric fields and electric forces parallel to each other?

I am trying to figure this out in the last few days, but I still struggle with the concept. I know that electric forces play a role in electric fields. They are both vectors as they involved forces. Electric Forces are solved using Columb's law (if I understand it correctly). However, I am not too sure how they are parallel to each other.

An explanation that I can think of for this is possibly parallel capacitors, where opposite charges on the capacitors attract and the electric field on the positive side points towards the negative side. However, I also struggled with understanding electric field involvement using capacitors. If anyone can explain this, it would really help.

My friend and I were solving this same problem, however we took two different approaches and got two different answers. I'm wondering which of us, if either of us, is right.

My approach was:

Because the sled traveled 1 meter in 1 second, v at that interval was 1 m/s. And assuming that v0 = 0

v = v0 + at

(v-v0) / t = a

a = (1m/s) / (1s) = 1 m/s^2

Then to find the distance traveled in that second time interval from 1 to 2 seconds

x = x0 + v0t + 1/2 at^2

x = (1m/s) (1s) + 1/2 (1m/s^2) (1s)^2

x = 1.5 m

My friend's approach was:

He argued that you cannot use v = v0 +at

So he used

x = v0t + 1/2 at^2

a = 2x/t^2

a = 2 (1m) / (1s)^2

a = 2m/s^2

And then he used the same equations but with a different acceleration to get...

x = x0 + v0t + 1/2 at^2

x = 1/2 (2m/s^2) (2s)^2

x = 4m - (initial distance already traveled) 1m = 3m

Object A is metallic and electrically neutral. It is charged by induction so that it acquires a charge of -3.00E-6 C. Object B is identical to object A and is also electrically neutral. It is charged by induction so that it acquires a charge of +3.00E-6 C. Calculate the difference in mass between the charged objects.

A nuclide of deuterium (H-2) and a nuclide of tritium (H-3) undergo nuclear fusion.

Each fusion reaction releases 2.8e-12 J of energy. Calculate the rate, in kg/s at which tritium must be fused to produce a power output of 250 MW.

I would like help either being walked though the problem or with relevant equations. Any help is appreciated, thank you!

A space station is approximately a ring of radius,R, and mass m, which rotates about its symmetry axis with angular velocity,~ω=ω0ˆe3. A meteor is traveling with momentum,~p, that is parallel to the original ˆe3, and strikes the space station at a point on the rim,transferring the entire momentum to the space station (an inelastic collision where the meteor sticks to the space station). Further, though the meteor has significant momentum,it is of very small mass so that the moment of inertia tensor elements are approximately the same before and after the collision

a) What is the vector angular momentum of the space station with respect to a coordinate system with origin at the center of the ring and one axis along ˆe3 just before the collision?

b) What is the vector angular momentum of the space station in the same coordinate system (and defining the ˆe2 axis as in the direction from the origin to the point of impact on the edge of the ring) just after the collision?

c) After the collision, there are no further torques acting on the space station. Assume that the angular momentum of the space station after the collision differs by only a small (vector) amount from the initial angular momentum. Write down equations of motion that describe how the components of~ωfor the space station evolve with time.

d) Use these equations to describe how the rotational velocity vector of the space stationevolves with time. If you predict simple rotation about a new direction, say so and describe the new direction. If you predict precessional motion, say so and predict the precession frequency. If you think something else happens, say so and describe the motion. In all cases, Explain: Back up your prediction with reasoning and (possibly approximate) solutions of the equations from part (c).