Tagged Questions

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.

75 views

Potential Energy Problem

We know that, the potential energy of a particle is $U= mgh$ where $h$ is the height from the zero potential point. But what I have found in Resnick's Fundamental of physics book is that they ...
99 views

Acceleration orthogonal to movement direction

I've been told that acceleration orthogonal to an objects movement direction doesn't require energy. Thus when a satellite goes around the earth, the change in direction caused by gravity doesn't use ...
192 views

Is work-kinetic energy theorem useless?

This is how my book explains it: $W_{net} = \delta K$ Since the net work is tied to changes in kinetic energy and changes in speed, a mass must accelerate in order for net work to be nonzero. ...
98 views

Exerting force upon oneself in space

In space, there is no friction or forces of resistance of any kind, so I would assume that if two people were in space and one of them punched or pushed the other, the person upon which the force was ...
672 views

Block slides down a movable ramp, 2 approaches yields different answer

My Question is exactly as this Phys.SE post: block slides on smooth triangular wedge kept on smooth floor.Find velocity of wedge when block reaches bottom The Problem is I used 2 methods Momentum/...
101 views

We all know that $f = ma$. But for finding displacement, we always use: $$s = s_0 + ut + \tfrac{1}{2} a t^2$$ My sir, i don't know why for some reason uses this weird method: $$F = \frac{ms}{t^... 2answers 286 views Which of these two forces is stronger: static friction or kinetic friction? [duplicate] Which of these two forces is stronger: The force of static friction or the force of kinetic friction? I am having a hard time understanding this concept of friction, so please explain your answer! 1answer 137 views When will the pringles can fall? When I'm pushing a tall, cylindrical object stood on its end (like a Pringles can) I can push it near its bottom, and it will slide forwards, or push it near the top, and it will topple over. So, ... 3answers 450 views Is the center of mass of an object just a convention? I am currently studying moments. The concepts are fairly obvious, but there is one thing I don't understand: the concept of center of mass. Why do we consider that the weight of a uniform object is ... 2answers 896 views How much force can bolt cutters exert? [closed] What's the mechanical advantage of an ordinary, let's say, 3 feet long bolt cutters? How many pounds can they exert? I'm asking because I have a lock which is apparently immune to over 9 tons of ... 1answer 74 views Space and motion When we throw a ball upwards sitting in a running bus or train it directly comes to our hands but when we do the same sitting on a moving motorcycle the ball falls backwards. Why? 2answers 1k views What are absolute space & time? Why are they not absolute in reality? As said by A.P. French in Newtonian point of view: Space is a sort of stationary three-dimensional matrix into which one can place objects or through which objects can move without producing any ... 4answers 689 views Why are we still teaching Newtonian physics if it's “false”? [duplicate] Why are we teaching an outdated theory when the math in general relativity isn't that hard? I really don't see a reason why we should teach a highly oversimplified theory in our schools. For me, it's ... 2answers 95 views What if the centripetal force were acting outward? Centripetal force is the centre-seeking force & is responsible for circular motion. But what if the centripetal force were acting radially outward? What would happen then? 2answers 878 views What are the conditions for a complete circular motions? Im a high school student and last week I learnt about vertical circular motion was thinking about this today, that what conditions are to be met in order to complete circular motion. First I thought ... 2answers 313 views How is the linear momentum conserved in this system? Let there be a block on a frictionless surface . Let an agent constantly exert an invariable force , say F on the block and does positive work by displacing the block by d unit. Here, the system ... 4answers 169 views Can you travel through the air using falling rubble? As seen below in Dragonball Z, we can see Uub jumping from one piece of rubble to the next to reach Goku in mid air. This kind of scenes are seen often in cartoons, so it made me wonder if physically ... 2answers 236 views “Rocket in a box” thought experiment Here's a thought experiment that I came up with a while ago. It might be hard to visualize, so I'll describe it as best I can. Take a rocket in a vacuum, in outer space. Attach a large "box" to the ... 2answers 724 views How can Excel be used to model the flight of a rocket? [closed] Firstly, sorry for any silly mistakes or improper use of this website - this is my first time using it! I am trying to use Excel to model the flight of the Apollo 11 Saturn V rocket using the real ... 2answers 344 views Finding coefficient of friction between block and plane [closed] An inclined plane makes angle \theta with horizontal. Upper half plane is perfectly smooth where as lower half is rough. The block of mass m starts sliding from top. If the block again comes to rest ... 4answers 167 views Is it possible to prove that projectiles with drag will not travel in a parabola under the theory of classical mechanics? Can you prove that projectiles will travel in a parabola, provided the acceleration due to gravity g does not vary significantly along the trajectory? This should take air resistance into account. I ... 4answers 871 views Why doesn't an orbiting body keep accelerating? As a physics newbie I'm trying to get a grip on basic orbital mechanics. I think I'm beginning to get grasp on how bodies interact with each other. When a body approaches another body it accelerates ... 1answer 261 views Naming vectors in free body diagrams Is there a convention for naming the vectors? Suppose there is a box on a table. I'm going to draw the forces acting on the box. So I focus on the box and ignore forces acting on the table, the ... 1answer 1k views Moment of Inertia of a sector of a circle [closed] I am trying to find the moment of intia about its centre of a sector of a circle of radius a, mass m and angle \pi/3. I have found the answer it is \frac{1}{2}ma^2 but originally tried a ... 1answer 540 views Kicking a soccer ball I wonder which type of kicking may cause the ball to go a larger distance? One way is kicking the ball when it is at rest and another is kicking a moving ball in the opposite direction. If the ball ... 3answers 308 views Pendulum (highschool) I have a question concerning pendulum. On our physics lessons we built simple pendulum consisting of weight and a thread (\ell=0.31 m). We tried to calculate g from the well known formula$$T_m =...
I'm supposed to shoot a projectile from the origin to a point $(x_0 , y_0)$ with minimal initial velocity $v_0$. (no air resistance; regular gravity) The flight time should be $T=\frac{x_0}{v_x}$. ...