# Tagged Questions

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### Find the angle and force constituent [on hold]

See picture for the problem description. I know of one way to solve this problem: Use the law of cosines to obtain: $$500^2=F^2+750^2-2 \cdot 750 \cdot F \cdot \cos(30°)$$ Rearranging and ...
0answers
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### At time $t=0$, what are the magnitude and direction of the perpendicular component of dp/dt? [closed]

In the dark in outer space, you observe a glowing ball of known mass 4.6 kg moving in the xy plane at constant speed in a circle of radius 7 m, with the center of the circle at the origin (< 0, 0, ...
2answers
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### If an asteroid were threatening the Earth, could I deviate it just by jumping on it?

An impact by a 10 kilometres asteroid on the Earth has historically caused an extinction-level event due to catastrophic damage to the biosphere. There is also the threat from comets coming ...
1answer
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### Reflection - reaction force direction

Let's say object hits a wall. When the object is reflected does the direction of the reaction force caused on the wall looks like the red arrow ? Does that direction depends on how "strong" object is ...
5answers
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### Forces as vectors in Newtonian mechanics

I seem to be confused about the nature of forces as vectors, in the basic Newtonian mechanics framework. I know what a vector is as a mathematical object, an element of $R^3$. I understand that if a ...
4answers
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### Find a central force given the orbit

I've been trying to solve the following problem for a long time. Let's consider a particle of mass $m$ in $\mathbb{R}^3$ with polar coordinates $(r,\theta,\phi)$. The particle moves on the orbit ...
3answers
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I'm a bit confused with some notation I encounter in physics calculus. Consider this: Taken from here. Integration operates on functions, correct? What does it mean to integrate $\frac{d{\bf ... 2answers 53 views ### Free vs bound vectors and torque When considering basic Newtonian mechanics, we can treat vector as free and move their point of application at will. This is consistent with the affine nature of Euclidean space. However, when ... 4answers 133 views ### If the velocity vector of a moving particle is always perpendicular to the position vector, is the path a circle? A Newtonian physics question: If the velocity vector of a moving particle is always perpendicular to the position vector, is the only possible path a circle? What if the magnitude of the velocity ... 1answer 89 views ### Relative wind velocity explanation - understanding Irodov problem 1.6 I am having trouble understanding the reasoning behind the solution in this Irodov General Physics problem. The problem is 1.6: 1.6. A ship moves along the equator to the east with velocity vo = ... 1answer 80 views ### What are some good resources for learning how to apply vectors in physics? Although I don't have any problems with vectors when using them in Mathematics but I am having a hard time using them in physics. It is really frustrating me. Can you please recommend me some good ... 2answers 63 views ### 2D vector components Can any equation with a vector e.g. velocity be used with just the horizontal or just the vertical components, I am thinking of equations like Newton's laws, conservation of linear momentum etc. So ... 4answers 174 views ### Sum of acceleration vectors If a point mass has some accelerations$\mathbf{a_1} $and$\mathbf{a_2} $, why is mathematically true that the "total" acceleration is$\mathbf{a}= \mathbf {a_1}+\mathbf {a_2}$? 1answer 195 views ### Finding angular momentum about the center of mass? If we have a couple of particles of an equal, unknown mass: $$r_{+} = (c + e^{-Bt} \cos({\theta}))\textbf{x} + (d + e^{-Bt} \sin({\theta}))\textbf{y}$$ $$r_{-} = (c - e^{-Bt} ... 1answer 155 views ### Where do these formulas for an object being pushed up an incline come from? [closed] An object on an incline with an angle \theta is being pushed at constant speed. Constant speed implies a = 0. Because F=ma and the object must have mass greater than 0. If I want to find the ... 2answers 96 views ### Animating an Acceleration Vector - Acceleration of object on a crested path in gravitational field So I was reading in Chapter 3 of my textbook, Sears & Zemanksky's University Physics with Modern Physics by Young and Freedman, 13th Edition, and the discussion took us to a definition of the ... 1answer 307 views ### Line of action force The task is to reduce the two forces into a single net force and then find the equation of its line of action. I chose to find the net force and momentum with respect to the origin. The magnitude of ... 1answer 62 views ### Some subtleties in direction of drag force Consider a body released from a height h and assume a drag force is linearly proportional to the velocity. Then by Newton's Second Law,$$m\mathbf{\dot{v}} = \mathbf{F_g} + \mathbf{F_{drag}} = ... 0answers 73 views ### Vector Derivative Transport Theorem Application I have a position vector in frame A, the derivative of which I want to take relative to an observer in frame B. I apply the Vector Derivative Transport Theorem. The obtained velocity vector is left in ... 2answers 159 views ### Difference between the two equations for acceleration I came upon this while studying S.H.M. Well,is there a difference between writing $$a=\frac{dv}{dt}\;$$ and $$a=v\frac{dv}{dx}\;$$ do they differ on the basis of one being a vector and the other ... 2answers 61 views ### Position with respect to time with friction I'm interested in equations of motion when friction is present for a little graphical side project I am working on. I'm really rusty with physics, so I apologize if this is a basic question or doesn't ... 3answers 5k views ### Vertical and horizontal components of forces and vectors I'm getting a bit confused when finding components of vectors and forces. In problems for vectors, I've always known that if you want to get the components of a vector, you would use the following: ... 3answers 7k views ### Why work is a scalar and not a vector? Work (in physics) is a scalar but why? and why not a vector? 2answers 2k views ### Resultant of two forces acting in the same line I'm quoting the definition of Resultant of two forces acting in the same line from the book "A FIRST COURSE IN PHYSICS" one of whose authors is Robert Andrews Millikan: The resultant of two forces ... 2answers 208 views ### About vector form of friction I read a text on mechanics and in the chapter on friction, there written that the kinetic friction is in the form $$f_k = \mu_k F_N$$ where$f_k$is the kinetic friction,$\mu_k$is the kinetic ... 3answers 746 views ### How to determine direction of forces in a static problem? I am consistently getting this wrong. To me, in the picture below, it would make sense that the structure would be pulling downward, and the cable BD would be pulling upward - thus the system is in ... 1answer 66 views ### Asking the vector form of the equation about velocity In the undergraduate text of physics, the equation for velocity and displacement at constant acceleration are given in scalar form. For example, my text reads $$v^2 = v_0^2 + 2a(x-x_0)$$ But today, ... 1answer 491 views ### A very elementary question regarding force of friction When I first studied friction I faced f =$\mu$N where f is force of friction,$\mu$is coefficient of friction for the surface considered and N is the normal force for the body on surface. Now f is ... 3answers 190 views ### Mechanics Problem I'm trying to follow Feynman's lecture. Unfortunately I'm a bit stuck on a small piece, so if you could show me what I'm doing wrong then I'd greatly appreciate your help. I want to exactly know how ... 1answer 277 views ### Solving inclined plane using diff. frame I was trying to solve frictionless inclined plane problem using a diff. frame as shown in the figure, and can't figure out that acceleration along the plane = g.sin(Θ), but I think it should be = ... 1answer 432 views ### A Lawnmower Problem For my physics class we were just given an exam that asked the following: A 12Kg lawnmower is pushed with a constant force along the 30* handle with 80N. Break the Forces into its vector ... 1answer 107 views ### Finding The Obtuse Angle [closed] I am working on a simple force problem involving inclines. I found a reference of$48^\circ$, in the third quadrant; now, to find the obtuse angle, do I subtract that value from$270^\circ$, or do I ... 2answers 257 views ### Conservation of Linear Momentum with respect to a given direction Is linear momentum conserved in any direction? More specifically, if you project all momentum vectors in a system onto another vector, will momentum be conserved? I know that momentum is conserved ... 2answers 129 views ### Showing$ m\int \frac{d\textbf{v}}{dt} \dot \normalsize \textbf{v}dt = \frac{m}{2}\int \frac{d(v^2)}{dt}{}dt\$

Can someone please explain how this equation is valid, using intermediate steps if available? $$m\int \frac{d\textbf{v}}{dt} \dot \normalsize \textbf{v}dt = \frac{m}{2}\int \frac{d(v^2)}{dt}{}dt$$ ...
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### Question involving Vectors and Forces

This is a question I found in Mechanics for Engineers by Beer & Johnston. A 600-lb crate is supported by the rope and pulley arrangement as shown below. Write a computer program which can be ...
3answers
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### How do I find the tension in additional strings in this problem? [closed]

A mass of 5.00 kg hangs attached to three strings as shown in the figure (see image below). Find the tension in each string. Hint: Consider the equilibrium of the point where the strings join. ...
2answers
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### Vertical component of moving weight at a 45 degree angle

Here's an easier one. I use the leg press machine at the gym so I don't have to worrying about hurting myself while lifting heavier weight. The weight glides on a track that looks to be 45 degrees. ...
1answer
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### How Does force relate to velocity

I had originally asked this question on math overflow and it was suggested that I ask it here. So I know that a force will change the magnitude of velocity if it is at an angle other that 90 degrees. ...