# Tagged Questions

Object moving through space due to the exertion of a force.

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### Optimal axis of rotation of a baseball for lateral movement

Suppose a baseball travels at $90\;\mathrm{mph}$; what is the ideal axis of rotation for lateral movement of the ball? (two-seamer or cutter). So far I think that the following factors play a ...
18 views

### Calculation of stone dropping [on hold]

A stone dropped from a building of height $h$ reaches the ground after $t$ seconds in the air. From the building top, if two stones are thrown, one upwards, the other downwards, with same velocity $u$...
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### Skeptical of the “Cannon Shot Rule” [on hold]

What I consider a highly suspect figure was imparted to me today in a lecture and it very immediately did not sit well with me. To wit, this cannon shot rule (see here for a reproduction of the ...
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### Which weapon can transfer more energy to a projectile: sling or slingshot?

Which weapon can transfer the most energy to a projectile, a sling or slingshot? Each is totally powered by a person, one stores energy in elastic the other kinetically. Which can store and transfer ...
1k views

### What is the longest distance that can be jumped after swinging from a rope?

In the movie Mission Impossible 3, the main character Ethan Hunt tries to enter a building in Shanghai by swing through the sky, as shown below: The jump consists of 2 sections, the red part, which ...
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### Pls help me visualise this situation, I'm not able to understand it [on hold]

Find time of flight of projectile thrown horizontally with speed 50m/s from a long inclined plane which makes an angle theta= 45° from horizontal.
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### Minimum initial vertical velocity of a projectile

A basketball is launched by a person with an initial velocity $v$ at an angle $\theta$ from a height $L$ into a basket of height $H>L$ which is a horizontal distance $d$ from the person. ...
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### Projectile motion and bouncing [closed]

Prove that the number of bounces n after throwing an elastic ball on a frictionless surface with a known angle (j)relative to the horizon and the angle of the initial velocity is known also (k)..is ...
30 views

### projectile on an inclined plane [closed]

Is the time of ascent equal to the time of descent? I tried it but I am not being able to prove it mathematically.
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### Conservation of enegry in case of Exploding Projectile [closed]

Consider the following problem : A projectile of mass M explodes, while in flight, into three fragments. One fragment of mass $m_1 =\frac12 M$ travels in the original direction of the projectile. ...
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### How to calculate the elapsed time to reach x? [duplicate]

Can some one provide a guideline about how to solve this problem?
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### How to calculate the time for reaching 1/2 of the height for an object [closed]

I need to calculate the time for reaching the red object to the 1/2 of it's height. Can somebody provide me some guidelines?
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### Why golf balls travel faster if they spin?

From the book I have been given to read I found that balls spin due to the centripetal force but i am confused about how exactly do the resultant force causes it to spin and move forward about the ...
274 views

### I know that free fall in vacuum is independent of mass. But what happens in air?

Pardon me if this sound somewhat trivial to some of the highly qualified users here. So I know two objects will fall at the same rate if they are in absolute vacuum, so what I'm assuming is that the ...
514 views

### Projectile, air resistance and wind

So for my school project I am working on a projectile simulator and air resistance. So I have looked at this. Equations for an object moving linearly but with air resistance taken into account? ...
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### Does $y$-motion really have nothing to do with $x$-motion?

I am watching a Physics 1 for physical science majors on coursera.com, and in one of the concept tests there is a question that goes like this; "A bullet is fired horizontally from a rifle on the Moon ...
1k views

### In a 2D problem with a thrown object, why is the acceleration along the x-axis equal to 0?

I'm starting Physics, and I don't understand why the acceleration along the x-axis is zero for an object thrown near the surface of the Earth. This may be problem specific, but I wouldn't know since I ...
804 views

### Why does a coin falls faster when it's flipping as well?

From my experiments with measuring how fast a coin falls, I have consistently measured a faster falling rate for a coin that flips as it falls. As an example, a coin dropping on its edge from height ...
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### Simple harmonic motion mass between 2 buildings

I have a question, where I have a mass on top of a building, we give it initial velocity of $\sqrt{gd/2}$ then it starts colliding between 2 buildings, elastic collision. I have to find how many times ...
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### How jet engine works in vacuum

Its not about availability of oxygen for combustion of gases. I want to know since there is no air or friction providing things in vaccum, how the force applied by a jet engine get can make thrust to ...
380 views

### Projectile motion maximum distance to origin

Is there an elegant or easy way to derive the maximum distance from the origin to a point of the parabola created by projectile motion (assume initial position is the origin)? Other than ...
112 views

### Will a heavier or lighter tank shell / bullet/ etc. travel further given the same starting energy?

Let's say I have for example two tank shells, both being the same size and having the same shape. Let's say the starting energy is 100kg*m/s^2, and the one shell is 1kg, the other 25kg. 1kg * 10m/s^...
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### Projectile motion on an inclined plane [closed]

Two parallel straight lines are inclined to the horizontal at angle $\theta$. A particle is projected from a point midway between them so as to graze one of the lines and strikes the other at a right ...
264 views

### Projectile motion - calculate landing angle

A projectile is launched at a $45^\circ$ angle, aiming for a target at a distance of 15 feet away from, and $2$ feet below the starting position. I'm looking for equations to determine: The ...
239 views

### Find the force needed to accelerate body to a certain velocity for a certain time with respect to drag force

So, the problem is straightworward when we suggest that air resistance force is constant: $$\vec F = \frac {\vec V_1 - \vec V_0} {t} m / b$$  \vec V_0, \vec V_1 - \text {initial and final ...
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### Projectile motion with air friction force/resistance [closed]

We have to find the x (the distance, if you didn't know that then I'm not sure if you should be doing this problem) that the projectile travel during the time in the air until the time it hits the ...
1k views

### Is running in a zigzag helpful in avoiding being shot by an arrow? [closed]

Two people A and B start at a certain point. B runs away from A to another point. A shoots arrows at B. Is it helpful for A to run in a zigzag rather than in a constant direction? To be more ...
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### How relativity affects projectile motion?

If, for example, I'm in a train traveling on earth at $.99c$, and I drop a ball from a $1~\text{m}$ height inside that train how long would it take to hit the ground from the ball's frame of reference?...
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### Find the initial velocity's angle of a projectile knowing only the ratio between the horizontal distance traveled and max height

The ratio between the horizontal distance traveled and the launch height is 3 to 1. I think it is possible to find the angle given this information, but how exactly do you do it? I think it's arctan(2/...
62 views

### Free fall vs throw with air resistance

If I let a stone drop from a certain height and throw a stone from a certain height, with air resistance, which will reach the ground first? When I draw a free body diagram the air resistance in the ...
9k views

### Why do archery arrows tilt downwards in their descent?

In the movies, arrows shot into the air rotate so that during the descent, the arrow head hits ground first. What is the source of this angular momentum? It would seem that the bow string exerts a ...
50 views

### Maximum range in projectile motion (elliptical path)

Elementary Newtonian mechanics tells us that if a projectile is shot at 45 degrees from the ground, and a downward gravitational field is acting on it, it will follow a parabolic path and achieve ...
54 views

### How can I find the maximum height if I have changing acceleration?

I'd like to find the maximum height that a projectile reaches in motion if I have a non-constant acceleration. How would I do this? What variables do I need to know in order to calculate this? ...
126 views

### How can we theoretically calculate the number of balloons needed to stop a bullet?

After watching this video, I am interested in proving it mathematically. The problem is that how can we apply the conservation of momentum here to find the velocity of the bullet while we don't know ...
114 views

### Intercept of 2 moving objects at constant acceleration

I have to make a simulation in which a guided missile has to hit an incoming enemy missile.The enemy missile "T" is the one which has to be intercepted and is only affected by gravity, the guided ...
63 views

### Speed and motion

If you your traveling in a forward motion at a certain speed and throw an object in the opposite direction at the same speed shouldn't it fall straight down to the ground.
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### How to calculate initial acceleration of a projectile motion? [closed]

I have an object following a projectile motion, that hasn't got horizontal acceleration but only vertical -g. What is the acceleration that I have to use in the second law of motion (F = ma) in order ...
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### Terminal velocity after vertical launch

If an object is launched directly up at its terminal velocity, will it have enough time/energy to reach its terminal velocity again before it hits the ground, or will drag prevent this? In this case, ...
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Yesterday i got a MCQ in exam that a body in projectile motion with initial velocity 20m/s creating an angle of 60 degree with horizontal. What is its velocity at max. Height (A) 10m/s Or ...
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### Supergun Launching of Satellites

I should say first that I don't believe this is a feasible launch method, otherwise NASA and other space agencies would be using it by now. It's based on this BBC news story Saddam Hussein's Supergun ...
5k views

### How does humidity affect the path of a bullet?

Background Last night, I was reading the FM 23-10 (The U.S. army official field manual for sniper training), and I've noticed that they're potentially teaching snipers incorrect information. ...
2k views

### Does gravity slow down a horizontally thrown baseball?

I have a simple question: Does gravity slow down a horizontally thrown baseball? Assuming when a baseball is thrown it has a vertical velocity as well, does it slow does the ball? Any help is much ...
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### Simple mathematical model for a bouncing ball

I started coding a physics program that simulates gravity - specifically a bouncing ball - and I've already learned a lot researching the topic but the bounce still doesn't look quite right. I need a ...
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### Use equations to create a realistic problem [closed]

Given the following equations: $100$ m = $0$ m + ($50 \cos\theta$ m/s)$t_1$ $0$ m = $0$ m + ($50 \sin\theta$ m/s)$t_1$ - $\frac{1}{2}(9.80$ m/s2$) t_1^2$ I am supposed to make up/create a real-life ...
8k views

### Finding the max height of a ball launched as a projectile using work-energy

A ball is launched as a projectile with initial speed $v$ at an angle $\theta$ above the horizontal. Using conservation of energy, find the maximum height $h_\text{max}$ of the ball's flight. Express ...
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### Finding acceleration due to gravity of a 2D projectile

Can I find acceleration due to gravity of a 2D projectile given only the peak of the projectile, the point of impact, initial angle, and initial velocity? Specifically what is missing is the initial ...
47 views

### Why did Trebuchet have so long throwing arms?

Have a look at such an historical Trebuchet: As you can see, the throwing arm (left) is much longer than the weight arm (right). Law of conservation of energy says, potential energy from the ...
8k views

### Does an object's kinetic energy increase, decrease, or stay constant when it reaches terminal velocity while falling?

Does an object's kinetic energy increase, decrease, or stay constant when it reaches terminal velocity while falling?