In introductory mechanics, the momentum of a particle is its mass times its velocity. In electrodynamics, the momentum of a field is proportional to the cross-product of the electric field with the magnetic field. In special relativity, momentum is generalized to four-momentum.
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160 views
Deceleration of Vehicle off pavement
How would I calculate the deceleration of a vehicle (ATV), wheels locked, on dirt? How long would it take to halt? How fast is it decelerating?
I used this calculator, but it seems incorrect for a ...
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1answer
276 views
Force and Laws of Motion [closed]
While catching a fast moving cricket ball, why do fielders gradually pull back their hands backwards with the moving ball? Please advice which among the following is the correct answer. If both are ...
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0answers
82 views
Physics behind 2 different wall kicks
I'm looking at a situation where a sprinter starts at some distance x from a wall. The goal is to sprint to the wall, hit it, and get back to the start as quickly as possible. There are two ways ...
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0answers
126 views
water / solid body momentum exchange [closed]
When water is sprayed a at a solid object weather flat or concave is the momentum exchange the same? Because when water hits the flat object it simply goes outward or perpendicular to the object but ...
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3answers
169 views
Classical mechanics and the speed of a train-mosquito collision, when perfectly rigid bodies
This is all under the assumption that they are perfectly rigid bodies:
A train is moving at 300m/s.
A mosquito is moving directly towards it, head-on, at 4m/s.
When the mosquito and the train ...
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1answer
741 views
Violation of Newton's 3rd law and momentum conservation
Why and when does newtons 3rd law violate in relativistic mechanics? Check this link http://www.animations.physics.unsw.edu.au/jw/Newton.htm.
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1answer
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Determine KE of electron given momentum & mass [closed]
Some info:
wavelength of electron: $2.78 \times 10^{-10}$
momentum of electron: $2.38 \times 10^{-24}$
Determine KE of electron. In a provided hint: $KE = \frac{p^2}{2m}$. So I have:
$$KE = ...
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2answers
225 views
Newton's Third Law - Action and Reaction on space, what happen with the astronaut? [closed]
This is a question from my homework.
Imagine an astronaut doing a repair in his ship, "parked" somewhere in space where gravity result is zero. As he can not do the repair, gets nervous and throws ...
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1answer
253 views
Minimal kinetic energy during elastic collision [closed]
Two wagons, moving towards each other along a straight line, collide. The first wagon has the speed 3 m/s and the weight 3 kg. The second wagon has the speed 1 m/s and the weight 1 kg. The collision ...
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5answers
256 views
Does the rotational speed of a planet consistently become faster and faster given that there are no conflicting events? [closed]
Does the rotational speed of a planet consistently become faster and faster given that there are no conflicting events?
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1answer
105 views
Could a people do all sort of gymnastics movement in vacuum space? [closed]
Could a people do all sort of gymnastics movement in vacuum space? I asked this because I am worry about that the astronaut leave the space shuttle during emergency could not go back to earth by ...
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1answer
384 views
Question on Impulse-Momentum theory
A 5kg stone kicked by a student undergoes a velocity change from 6m/s
to 10m/s in 4 seconds;
---- What is the momentum change of the stone within the time interval?
---- What impulse ...
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1answer
136 views
Mathematical question on Collisions [closed]
A 2.5kg ball travelling with a speed of 7.5m/s makes an elastic
collision with another ball of ...
