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3 votes
Accepted

Is the answer given in the option wrong?

The answer sheet is correct. You are ignoring the statement “The direction of the motion of the object changed only once, at time t.” That means that the velocity was zero at time t. So before time t ...
Dale's user avatar
  • 103k
2 votes
Accepted

How to expand $(D_\mu\Phi)^\dagger(D^\mu\Phi)$ in $SU(2)$?

You appear to not appreciate your expression as a row vector dotted on a column vector (possibly sandwiching operators). I corrected your expression to $$\partial_\mu\Phi^\dagger \partial^\mu \Phi - \...
Cosmas Zachos's user avatar
2 votes

What does $v$ actually represent in pulley problems?

By your definition that $v=dl/dt$, $v$ is just the rate of change in the lengths of the rope segments supporting their respective masses. Here you define $v$ to be a scalar, since $l$ is also a scalar,...
hendlim's user avatar
  • 692
2 votes
Accepted

Question regarding gravitational force as external force

My doubt is if gravitational force is considered as an external force Yes, it is considered as an external force, an external conservative force. ...so how come can we apply Total mechanical energy ...
hft's user avatar
  • 21.8k
2 votes

Issue with simplifying the equation related to non-uniform acceleration

The equation $$ \frac {d v}{dt}= A+ B\, v^2 $$ with constant $A$ and $B$ is an example of a Riccati equation. The Wikipedi article shows you how to solve it.
mike stone's user avatar
  • 54.5k
2 votes

For an objective falling, reaching terminal velocity and then hitting the ground, how can I find the force it exerts on the ground?

Short answer: The given information is not enough. Long answer: You correctly noted that the force of the impact is related to the change in momentum. We take off from there. If we assume the duration ...
Saeed's user avatar
  • 216
1 vote

Strain energy stored in a bungee cord pulled at its midpoint

When a spring is halved, its spring constant $k$ is doubled. Because I'm treating this as a two spring system I need to double the value of $k$ that I'm using. Using a value of $k=280$ N/m gives $x=....
Imperator's user avatar
1 vote
Accepted

Buoyant force on a stick making an angle theta with the vessel

Divide the underwater world into two parts - the water and the stick. Suppose the water disappeared, leaving the stick. The force on the stick would be the weight of the stick. Suppose you replaced ...
mmesser314's user avatar
  • 40.8k
1 vote
Accepted

How to calculate the relative speed when three bodies are involved?

Just draw a principal vector diagram of separate movements : Add $\vec B + \vec C = \vec C~'$ and you will get woman velocity relative to the ground. Now subtract that from train's A velocity vector ...
Agnius Vasiliauskas's user avatar

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