Newtonian mechanics covers the discussion of the movement of classical bodies under the influence of forces by making use of Newton’s three laws. For more general discussion of energy, momentum conservation etc., use classical-mechanics, for Newton’s description of gravity, use newtonian-gravity.
-2
votes
1answer
53 views
Why is there no such thing as a body in a state of acceleration?
It appears that velocity is a quantity of motion meaning that all objects can have assigned to them a particular velocity. Through the application of forces (ex: gravity, E&m) we measure changes ...
0
votes
2answers
74 views
Will a helicoper which is hovering inside a closed box move with the box when we move it? [duplicate]
I got this micro helicopter to play with, you know that cheap double bladed ones you can find for $25 or so. Anyway last night I was on bed trying to sleep and I got this idea, what if we put the ...
0
votes
1answer
39 views
Is this a correct interpretation of pressure?
So I am told that pressure = Force per Area --> F/A..
When considering the units of Force I find that force = kg * m/s^2
When considering the units of Area I find that area = m^2
Thus the units of ...
5
votes
1answer
74 views
What if the lid of a pressure cooker was suddenly released?
My dad and I have tried to calculate the strength of the explosion if the lid was suddenly freed. We took some measures:
Lid mass: $0.7 \textrm{kg}$
Lid surface: $0.415 \textrm{m}^2$
Internal ...
0
votes
0answers
44 views
Determining the length of a Torsional Pendulum
Currently working on this question, however I'm not sure how to solve it.
As a pendulum swings in simple harmonic motion at the surface of the Earth, the angle the pendulum makes relative to its ...
3
votes
2answers
161 views
Nonuniform acceleration due to rubber rope
What I want:
I have a rubber rope which is $5m$ in length when not stressed and is able to stretch about $100\%$ (to $10m$ long). I want to accelerate a constant mass horizontally, which has ...
1
vote
2answers
53 views
How to determine a reaction force?
An object sits on an inclined plane. The weight of the object will have a normal and parallel component. I always thought that the reaction of the plane was simply the negative of the normal component ...
0
votes
3answers
91 views
Man in elevator, holding it, on a scale
This is the scenario where my mass is $60 kg$, the mass of the elevator is $30kg$, and due to a malfunction, I have to hold myself and the elevator at rest. The question is, if there is a weighing ...
0
votes
2answers
49 views
Escape velocity to intersection of two gravitational fields
Find the minimal velocity needed for a meteorite of mass $m$ to get to
earth from the moon. Hint: the distance between the center of earth
and the center of moon is $\approx 60 R_E$, and the ...
2
votes
1answer
51 views
I read a book saying bernoulli's flight equations didn't have as much impact on lift as most people think [duplicate]
I'm a computer scientist that likes to read about math and physics occasionally. A local author at a nearby aviation center brought bernoulli's flight equations into question.
It was clear enough ...
3
votes
1answer
70 views
Conservation of momentum in collision of two bodies
Suppose we have some ramp on wheels of mass $M$, standing on a
frictionless surface. A cart of mass $m$ moves with a certain velocity
$v$ towards the ramp. The cart moves up the ramp ...
2
votes
1answer
49 views
Oberth Effect in deep space
Does the Oberth effect only apply when in orbit of a planet or would a rocket generate more and more thrust (if kept on) even in deep space?
Wikipedia explains that the faster the rocket goes, the ...
4
votes
2answers
91 views
Thrust center in space
I have this dilemma: Suppose you have a space ship somewhere in deep space, where there is no drag force or substantial gravity. If the ship has a single engine situated in such a way that the center ...
0
votes
0answers
13 views
Determining the acceleration of one to another with three unknowns [closed]
Given the following image, how would you determine the acceleration of block A, and the acceleration of block B relative to A? I'm trying to include the pulley as part of block A but I cannot figure ...
-4
votes
1answer
47 views
High School Physics student needs help [closed]
A human cannon has a spring constant of 35 000 N/m. The spring can be extended up to 4.5m. How far horizontally would a 65kg clown be fired if the cannon is pointed upward at 45 degrees to the ...
1
vote
1answer
77 views
Gravitational potential energy of mass between two planets
Suppose I want to launch a rocket from earth to some point $O$ between the center of earth and the center of moon (on a straight line connecting their centers), where the gravitational force of the ...
3
votes
1answer
60 views
Tension of rope in the gravitational field of earth
Two balls of mass $m$ each one are connected with mass-less rope with
the same length as the radius of earth. The system is in free fall.
Prove that the tension of the rope when the nearest (to ...
0
votes
2answers
194 views
Two blocks connected by spring on frictionless surface and Newton's third law
Suppose there is the following situation:
Blocks $A$ and $B$, with masses $m_A$ and $m_B$, are connected by a
light spring on a horizontal, frictionless table. When block $A$ has
acceleration ...
2
votes
0answers
23 views
What diameter is used to calculate stress in an elastomer whose cross sectional area changes continuously when streched?
Consider a cylindrical rope of rubbery elastomer with a radius (in inches) equal to the square root of the inverse of $\pi \rightarrow \sqrt \frac{1}{\pi} $ so that the cross sectional area is $1 \, ...
1
vote
1answer
142 views
Projectile along incline [closed]
A particle is projected with velocity $u$ from the bottom of an inclined plane whose inclination with the horizontal is $\beta$. If afterwards the projectile strikes the inclined plane perpendicular ...
0
votes
1answer
48 views
Finding the moment of inertia through superposition?
Let's say I have a body consisting of two homogenous spheres/balls that touch each other. I also have a body fixed coordinate system which consists of that body's principal axes. I know the the moment ...
2
votes
1answer
264 views
How does the resistance force on a rolling ball depend on the ball radius?
A billiard ball set gently rolling on a billiard table slows and stops, because it is decelerated by resistance forces at the contact between the ball and table.
I expect the magnitude of the ...
6
votes
0answers
99 views
What determines the angle of the cushion on a pool table?
If you look at the cushions (bumpers) on a pool table, you'll see that they're not vertical. They're tilted inwards. About 10 years ago, I came across a physics exam in which one of the problems ...
0
votes
0answers
35 views
What is the total work done in this problem? [closed]
A 1800 kg trick airplane is 450 m in the air. At this point the plane takes a dive
with an initial speed of
42 m/s and accelerates to 64 m/s, dropping
a total distance of 120 m.
(a) Using the ground ...
0
votes
0answers
37 views
Maximum Height of Potato [closed]
I have a bit of a problem. We made potato launchers and launched the potato's into the air. I need to find out what the maximum height my potato reached was. The givens I have are the following:
Mass ...
0
votes
3answers
2k views
Torque required to turn a drum/barrel
I need to spec a motor to turn a mixing barrel. The barrel contains loose earth and can be filled to a maximum of 50% of its interior volume. It is a horizontal cylinder, and will rotate through its ...
0
votes
1answer
66 views
Change in speed of a satellite
Suppose there's some satellite orbiting the earth in circular motion. Suppose there's an asteroid that hits the satellite in the same direction as the instant velocity vector of the satellite. The ...
0
votes
0answers
28 views
Understanding Kepler's $2^{nd}$ law in terms of angular momentum conservation
A) Explain how Kepler's $2^{nd}$ law - "The radius vector from the Sun to a planet sweeps out equal areas in equal time intervals" - can be understood in terms of angular momentum conservation.
I ...
0
votes
2answers
76 views
How to calculate time for ball to reach plane while considering mass, gravity and wind resistance?
The scenario that I'm having is such that a ball of radius $15mm$ is thrown from a location point $\vec{p}=(2, 5, 2)$ in a direction of $\vec{d}=(3, 0, 4)$. The initial velocity is $30m/s$. There were ...
0
votes
0answers
42 views
What is to be considered a “body” in physics?
Well, the question says it all; is there a definition of body in physics? What is to be considered a physical object and what it cannot?
0
votes
1answer
159 views
Calculating a 2D collision between two perfectly circular disks
Assume I have two disks, $p_1$ and $p_2$, of radius $r$, with their own velocities (preferably in $(x,y)$ form, but $(m, \theta)$ works too) and masses (unit-less, but same unit) collide in two ...
5
votes
1answer
448 views
Dependence of Friction on Area
Is friction really independent of area? The friction force, $f_s = \mu_s N$. The equation says that friction only depends on the normal force, which is $ N = W = mg$, and nature of sliding surface, ...
6
votes
2answers
4k views
How is distance between sun and earth calculated?
How has the distance between sun and earth been calculated by scientists?
and size of sun?
Thanks,
0
votes
1answer
207 views
How should I apply conservation of energy to this problem?
A block rests on a table. Then the block is pushed by a spring and slides across the table until it falls to the ground. The mass of the block is $1.30\text{ kg}$, the spring constant $550\text{ ...
4
votes
3answers
325 views
A fly in an accelerating car
A fly is flying around in a car, the fly never touches any surface in the car only fly’s around in the air inside the car. The car accelerates. does the fly slam in to the rear window. or does the fly ...
0
votes
1answer
40 views
Rotational Dynamics
In studying rotational dynamics of a rigid body , I can't seem to understand why you can solve the problem correctly only using certain points in a body and not all ? Means angular momentum and torque ...
1
vote
1answer
74 views
Given a potential energy function, find expression of the force of a particle?
This comes from an AP review packet. I'm given a potential energy functon, $$U(r)=br^{-3/2} + c,$$ where $b$ and $c$ are constants, and need to find the expression for the force on the particle.
...
0
votes
2answers
278 views
Center of gravity of vehicle and vehicle performance
I am interested to know how does CG of vehicle plays role in the Fuel economy and the vehicle performance. Does CG of vehicle has anything to do while accelerating of your vehicle. I am a student, ...
0
votes
1answer
36 views
Period of oscilation [duplicate]
Two masses $m_1$ and $m_2$ are connected by a spring of spring constant $k$ and slide freely without friction along horizontal track. What is period of oscillation? No force influence.
-1
votes
2answers
79 views
How to determine Center of Gravity? [closed]
I came across this question while having conversation with one person.
We know that Center of Gravity of a solid cube is at the intersection of connecting the opposite vertex of the cube.
Suppose, you ...
0
votes
1answer
50 views
Problem about moments and equilibrium. [closed]
A plank is on top of 2 branches. It is in contact at 2 points, A and B. The plank is 90 cm long. A is on the left of B. A is 15 cm from the left end of the plank. B is 20 cm from the right end of the ...
2
votes
2answers
83 views
Parabolic motion (experiment)
We performed a laboratory, performing six releases of a sphere with angles $15^\circ,30^\circ,45^\circ,60^\circ,75^\circ,40^\circ$ a parabolic movement, took five distances for each angle, the initial ...
0
votes
0answers
40 views
Trajectory the body thrown at angle to the horizon
I need to simulate some body, thrown at some angle to the horizon and at some azimuth.
What would be $x(t)$, $y(t)$ and $z(t)$ involving $g(h)$, air resistance (with $\rho(h)$), Coriolis effect and ...
0
votes
1answer
82 views
Energy needed to lift and bring down an object
A mass of 0.5 Kg needs to be moved from point A to another point (B) which is 1 meters above point A. The time for this movement should be 0.2 seconds, then the mass is kept at position B for another ...
1
vote
1answer
30 views
Why frequency and tension doesn't change in the two medium?
I am reading a book about wave mechanics. There are two different cord (one light and one heavy) connected together, one person waving the lighter one, the wave transverse to the right from the ...
-2
votes
0answers
64 views
Man ,Pulley, block system? [closed]
In the figure $m_{A}=m_{B}=m_{C}=60 kg$. The coefficient of friction between $C$ and ground is $0.5$, $B$ and ground is $0.3$, $A$ and $B$ is $0.4$. $C$ is pulling the string with the maximum possible ...
2
votes
1answer
107 views
Wedge and Sphere problem
A sphere of radius $R$ is in contact with a wedge. The point of contact is $\frac{R}{5}$ from the ground as shown in figure. Wedge is moving with velocity $20~\text{m/s}$ towards left then the ...
0
votes
1answer
83 views
A small oscillations of a rod on the cylinder
Let's have the next case.
A rod (with mass $m$, length $L$ and a momentum of inertia $I$) at the initial time is located on a cylinder (with radius $R$) surface so that it's (rod's) center of mass ...
1
vote
1answer
112 views
Calculating the acceleration of a car
I'm trying to calculate the maximum acceleration a car can achieve with the current gear ratio. I am ignoring drag forces and friction to keep it simple.
I'm doing this by:
calculating the torque ...
3
votes
2answers
58 views
Two-body problem questions
I am self studying the two body problem and I'm stuck on the following:
I have given $$\ddot{\vec{x}}_1= - G m_2 \frac{\vec{x}_1-\vec{x}_2}{|\vec{x}_1-\vec{x}_2|^3}$$ and $$\ddot{\vec{x}}_2= - G ...
