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-2 votes

Oblique Projectile Motion

Here one of the correct answers is option D since range is maximum at 45 degrees. To find the other one we need the angle of projection of the body
Suchiiswar Paudmanabhan's user avatar
0 votes

Distance formula in kinematics?

your first equation, $d = v_it + \frac12at^2$, expresses the displacement the object ends up with at time t. the displacement is nothing but the change in position; and no matter what the initial ...
blue_birb's user avatar
1 vote

How do I know if a motion is 1 dimensional or 2 dimensional?

the main thing take away: physics does not care a about your coordinates. So if the thing is moving on: $$ \vec r(t) = t\cos{\theta}\hat e_1 +t\sin{\theta}\hat e_2 $$ thats linear motion in a plane. ...
JEB's user avatar
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6 votes

How do I know if a motion is 1 dimensional or 2 dimensional?

Both you and your teacher can be correct depending on what you mean by "dimension." In everyday experience, we generally consider dimensionality to be the number of independent parameters ...
Roger Yang's user avatar
7 votes
Accepted

How do I know if a motion is 1 dimensional or 2 dimensional?

Let's say you have the following motion (the red arrow) It looks 2D on this plot, since its motion changes both the $x$- and $y$-coordinates. However, if you redefine the axes like so: Then the ...
Allure's user avatar
  • 21.4k
4 votes

How do I know if a motion is 1 dimensional or 2 dimensional?

One dimensional motion is any kind of motion that happens on a line. There are many ways to define this. For example, you could say that the position vector of the particle is always $\vec{r}(t)=r(t)\...
agaminon's user avatar
  • 1,775
2 votes
Accepted

Work Done by kinetic friction in Circular Motion

In circular motion, your total displacement $$\oint \mathrm{d}\vec{s}$$ is zero, correct. But for work, you are not integrating just the displacement $\mathrm{d}\vec{s}$, but the quantity $\vec{F}\...
CompassBearer's user avatar
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
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
0 votes

What does it mean when vector quantity is negative?

Let $\vec v = v\,\hat v$ where $v$ is the component of $\vec v$ in the $\hat v$ direction. Then you can interpret $\vec {v'} = -v\,\hat v$ in one of two ways: $\vec {v'} = -v\,(\hat v)$ with $-v$ the ...
Farcher's user avatar
  • 97.9k
0 votes

What does it mean when vector quantity is negative?

"Negative" vectors only make sense in one dimension. Such vectors don't have a direction only orientation. It makes sense to use + and - to denote orientation because two vectors of equal ...
Alien from future's user avatar
0 votes

What does it mean when vector quantity is negative?

Vectors don't have a "sign", per se. You can choose to represent a vector in terms of its components. For example, suppose we had some velocity vector $\vec{v}$. You can decompose $\vec{v}$ ...
Andrew's user avatar
  • 51.2k
0 votes

What does it mean when vector quantity is negative?

The sign of a vector is mostly a result of the coordinate system chosen, or another arbitrary definition. For example, negative acceleration means an object is slowing down is only true if the ...
JEB's user avatar
  • 35.4k
6 votes

What does it mean when vector quantity is negative?

$-\vec v$ is a vector which has the same magnitude as $\vec v$ but points in the opposite direction. So $\vec v + (-\vec v)=0$.
Dale's user avatar
  • 103k
0 votes

Motion of person in bus in inertial and non-inertial frame

A person is sitting in a bus that is moving with constant velocity, due to friction their is no relative velocity between bus and the person. If the bus is moving with constant velocity, no friction ...
Bob D's user avatar
  • 73.7k
0 votes

Motion of person in bus in inertial and non-inertial frame

These effects are often called ficticious forces. I'll often call them pseudo forces, but I have found the best way to think of them is as accelerations. When you do the equations of motion in a non-...
Cort Ammon's user avatar
  • 50.2k
0 votes

Motion of person in bus in inertial and non-inertial frame

What we feel in an accelerating vehicle is the force from the seat back that is pushing us forwards so that we accelerate along with the vehicle. What we unconsciously assume is that there must be an ...
gandalf61's user avatar
  • 56.4k
0 votes
Accepted

Motion of person in bus in inertial and non-inertial frame

My doubt is, if the fictitious force is not a real force why do we still feel a force pushing us backward while sitting in accelerating car? If you were somehow levitating in the bus as it ...
BioPhysicist's user avatar
  • 57.2k
0 votes

Motion of person in bus in inertial and non-inertial frame

I think, If you are considering acceleration in any sense, you need to include the reference frame in which the acceleration is taking place. In 2nd person frame of reference, the one observing from ...
Samradh Bhardwaj's user avatar
0 votes

What is the correct way to think of position?

Yes, that's correct. Position is a point in $n$-space, and velocity is its derivative. Integrating velocity, you get the change in position, a.k.a. displacement. Formally, position is $\vec r=x\vec{\...
controlgroup's user avatar
0 votes

What is the correct way to think of position?

Indeed. In many Physics textbooks position is assumed to be a vector in 3D space, defined as : $$ \textbf{r} = x \hat{\textbf{i}} + y \hat{\textbf{j}} + z \hat{\textbf{k}} \tag 1$$ then velocity is ...
Agnius Vasiliauskas's user avatar
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
0 votes
Accepted

Different results of Range of a projectile

The range equation you are using gives you the horizontal distance traveled by the projectile while it’s above its initial launch elevation. Only if launched from the ground will its velocity be zero ...
Bob D's user avatar
  • 73.7k
1 vote

Different results of Range of a projectile

This is a really weird question... You're talking about two entirely separate things. Usually when we refer to range, we mean the linear distance covered between point of takeoff and point of landing. ...
Ekarshi's user avatar
  • 63
1 vote

Different results of Range of a projectile

Your range equation assumes that the projectile stops at the same height it is launched at. If the launch angle is $0^\circ$, then it does not have an initial upward velocity component, and hence it ...
BioPhysicist's user avatar
  • 57.2k
5 votes

How much time does it take for an object to fall from space?

If the body has no angular momentum (no tangential speed with respect to Earth), what you want to solve is Newton's second law in this form: $$m \frac{\mathrm d^2h(t)}{\mathrm dt^2}=-\frac{GMm}{(R_{\...
Mauricio's user avatar
  • 5,568
2 votes

How much time does it take for an object to fall from space?

Assuming the fall is purely radial and neglecting any fancy rotation and coriolis effects, you would obtain a single differential equation: $$\frac{GM_e}{(R+h)^2} = -\frac{\mathrm{d}^2 h}{\mathrm{d}t^...
CompassBearer's user avatar
3 votes

How much time does it take for an object to fall from space?

The solution can be found on Wikipedia, the time $\rm t$ to fall from $\rm r_0$ to $\rm r_1$ is $$\rm t=\left(\sqrt{\frac{{r_1} \left(1-\frac{{r_1}}{{r_0}}\right)}{{r_0}}}+arccos\left(\sqrt{\frac{{r_1}...
Yukterez's user avatar
  • 12.4k
0 votes

How to find the resultant speed component, and finding the angle in which the trajectory had hit the ground?

Any velocity can be considered to be the vector sum of two component velocities. For a projectile it is convenient to resolve the velocity into a horizontal component ($v_x$) which can be considered ...
KDP's user avatar
  • 6,102
0 votes
Accepted

How to find the resultant speed component, and finding the angle in which the trajectory had hit the ground?

For what purpose is the Pythagorean theory used although this context has nothing to do with trigs and triangular equations. This context does have to do with right triangles and trigonometry. ...
Thomas Fritsch's user avatar

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