# Tag Info

### 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

### 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 ...
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. ...
• 35.4k

### 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 ...
• 469
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 ...
• 21.4k

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 ...
• 103k
1 vote

• 689

### 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 ...
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 ...
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 ...
• 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. ...
• 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 ...
• 57.2k

### 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}...
• 12.4k

### 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 ...
• 6,102