Tagged Questions
-3
votes
0answers
20 views
Length Traveled from Complete Stop [closed]
A one-meter long rifle fires a bullet at a velocity of 800 m/s. What is the average acceleration experienced by the bullet when it is fired? (Hint: You need to find the time it takes the bullet to ...
-1
votes
0answers
34 views
Velocity versus time graph [closed]
A stone is thrown at an angle of $45^0$ above the horizontal x-axis in the +x-direction. If air resistance is ignored, which of the velocity versus time graphs shown above best represents $v_x$ ...
1
vote
3answers
65 views
Relation between the time, velocity and acceleration
This is question from I.E. Iredov's General Physics:
$1.22$ : The velocity of a particle moving in the positive direction of the $x-axis$ varies as $v = α \sqrt x$, where $α$ is a positive ...
-4
votes
0answers
35 views
How to calculate average speed when time is greater than distance? [closed]
I understand that average speed is calculated as $\frac{distance}{time}$ however this question says the time is greater than speed. Here's the question:
A bicycle travels 15 Km (kilometers) in 30 ...
6
votes
4answers
121 views
Integrating radial free fall in Newtonian gravity
I thought this would be a simple question, but I'm having trouble figuring it out. Not a homework assignment btw. I am a physics student and am just genuinely interested in physics problems involving ...
1
vote
3answers
123 views
How can I solve for time without knowing the vertical velocity?
A guy posted this problem on a forum:
There is a bird sitting on a pole of height h. you throw a rock at it and the moment the rock leaves your hand the bird starts flying horizontally away from ...
0
votes
1answer
78 views
Reachable area of cannonball given fixed initial speed [closed]
The trajectory of a cannonball fired from the origin with initial speed $v_0$ at an angle $\theta$ is given by
$$y = x\tan\theta - \frac{g}{2v_0^2 \cos^2\theta}x^2.$$
For fixed $v_0$, at what angle ...
0
votes
0answers
26 views
Defining collision point in 3D [closed]
I have a problem with finding collision point of two objects with given speed vectors in 3d. Eg:
...
0
votes
2answers
83 views
Given Angle, Initial Velocity, and Acceleration due to Gravity, plot parabolic trajectory for every “x”?
Given any Angle -> 0-90
Given any Initial Velocity -> 1-100
Given Acceleration due to Gravity -> 9.8
Plot every x,y coordinate (the parabolic trajectory) with cartesian coordinates and screen pixels ...
0
votes
3answers
98 views
Solve for Initial Velocity of a projectile given Angle, Gravity, and Initial and Final positions?
I've found equations http://www.physicsclassroom.com/Class/1DKin/U1L6a.cfm for solving everything (and rearranged to solve everything) to do with projectile motion EXCEPT this, even though it should ...
0
votes
1answer
79 views
Kinematics with non constant acceleration
A particle experiences an acceleration described by
$$
a=kx^{-2}
$$
where x is the displacement from the origin and k is an arbitrary constant.
To what value does the velocity v of the particle ...
0
votes
0answers
35 views
Inelastic relativistic collision [closed]
I have to solve the following problem:
A particle of rest mass, $m_1$, and velocity $v_1$ collides with a stationary particle of mass $m_2$. Find the rest mass $m$ and velocity $v$ of the resultant ...
3
votes
2answers
66 views
Sign of acceleration
I'm developing an application using accelerometer sensor. I'm not good at physics so forgive me if the question is trivial. If I have 3 values of acceleration: $x$, $y$, $z$, I find acceleration ...
4
votes
2answers
1k views
Help me get out of a speeding ticket
I was driving uphill from a complete stop for a distance of .4 miles estimated to take 1 minute in a navigation app. I was pulled over right after cresting the hill. The cop had me on radar going ...
0
votes
0answers
61 views
An unmarked police car passed by a speeding car [closed]
Hi I'm trying to solve the problem
An unmarked police car traveling at a constant speed of 95 km/h is passed by a speeder traveling at 140 km/h. Precisely, 1.00 s after the speeder passes, the ...
0
votes
1answer
45 views
Projectile's angle in midflight
For a missile travelling from (0,0) at angle $\theta$ (to the horizontal) and initial velocity $u$, the y (vertical) position at time t is given by
$s_{y} = u\sin (\theta) t - 0.5gt^{2}$
and the x ...
0
votes
1answer
67 views
Circular motion and centrifugal force
Assuming a race car drives around in a circle of radius r, center (0,0), linear velocity v, and ignoring centrifugal forces and friction I can calculate the position at any time, t.
Angular velocity
...
1
vote
2answers
148 views
Projectile Motion with Drag
The overall goal is to write a Mathematica program that will compute the launch angle that will yield the greatest range with using [RandomInt] function, but I was having trouble with the physics.
In ...
0
votes
1answer
65 views
Kinematics question [closed]
An electric train accelerates uniformly from rest to a speed of 20m/s which it maintains until the brakes are applied. It is then brought to rest by a uniform retardation equal in magnitude to twice ...
1
vote
2answers
90 views
Doubt in Kinematics
I know that this isn't the place for such basic questions, but I didn't find the answer to this anywhere else. It's pretty simple: some particle moves in straight line under constant acceleration from ...
1
vote
0answers
70 views
What is the initial velocity of a projectile so that it passes through a target point in its trajectory? [closed]
Let's say I have a projectile being thrown by a player in my 2-D game. I want to work backwards and find the initial velocity to apply to the projectile such that it passes through a target point in ...
1
vote
0answers
64 views
Getting pairs of angle and velocity for a projectile to a given destination
I'm trying to calculate the initial velocity $v_0$ and angle $\theta$ for a given destination $(x, y)$ with a launch height of $y_0$. Obviously there will be a set of pairs of velocity and angle that ...
1
vote
1answer
68 views
Shooting a bullet at a system of blocks [closed]
So, I made this question up myself.... and I'm curious about the answer. It requires only secondary-school-level knowledge of physics:
You have a surface (ground) with a certain coefficient of ...
0
votes
0answers
48 views
Driving around a road block? (Quick, turn the wheel !?) [closed]
Consider a car driving with given speed $v$ head-on towards a road block of a certain width.
Car and road block are already so close to each other that a collision would not be avoidable anymore by ...
0
votes
2answers
117 views
How can I add an acceleration vector to a velocity with a different direction?
I am in my last year of high school and am struggling with some homework. I'm sorry if this question is incredibly stupid, but I simply can't find the answer in my notes.
If I have an object with a ...
0
votes
2answers
141 views
Equation of motion for average acceleration
I am trying to solve the following:
A man of mass 83 kg jumps down to a concrete patio from a window ledge only 0.48 m above the ground. He neglects to bend his knees on landing, so that his ...
1
vote
0answers
51 views
I need help with the following Physics' questions [closed]
I need to know which formulas and the step-by-step answers for the following physics questions:
1. You throw a ball upward with an initial speed of 7.0 m/s, and it returns to your hand o.92 ...
1
vote
0answers
47 views
A 0.1kg ball of dough is thrown up with a velocity of 15m/s. What is the momentum halfway up? [closed]
I know that $p=mv$ and (0.1kg)(15m/s)=1.5 kg m/s and the momentum at the vertex is 0, but what is the momentum halfway up?
0
votes
0answers
54 views
At an acceleration of 2ft/s^2, how fast could I reach 9.8MPH? [closed]
Question title is self explanatory.
If I'm accelerating at $2ft/s ^{2}$, how long does it take to reach $9.8MPH$?
3
votes
1answer
87 views
How deep is the well, given this data?
A rock is dropped into a well. A timer starts when the rock is dropped and is stopped when the noise of the rock hitting the ground of the well is heard. How deep is the well?
Here's what I have so ...
5
votes
3answers
314 views
Why isn't average speed equal to displacement over time?
I'm in an introductory Physics course and I need help!
During a one-hour trip, a small boat travels 80.0km north and then travels 60.0km east. What is the boat's average speed during the one-hour ...
0
votes
0answers
60 views
Magnitude of object's angular acceleration [closed]
I'm studying for a physics exam today and am super stumped on a problem. Would love your help, or some guidance on how to solve it.
An object is being spun at an angular speed of 4.3 rad/s and ...
0
votes
0answers
76 views
Physics about plane take off simple find the acceleration problem [closed]
This was on my test, but I kinda botched it I think.
I was trying to use
V^2f = Vo^2 + 2a(delta x)
A plane must reach 226km/h to take off. Runway is 2000m. What's minimum acceleration needed? ...
0
votes
1answer
60 views
Is it necessary to know initial y velocity to solve this projectile motion problem?
A marble is launched horizontally off a 93.0-cm high table causing the marble to land on the floor 1.85 m from the base of the table.
a.) How long was the ball in the air?
b.) With what ...
1
vote
1answer
136 views
Projectile motion problem with upward acceleration and horizontal velocity [closed]
An electron in a cathode-ray tube is traveling horizontally at 2.10×10^9 cm/s when deflection plates give it an upward acceleration of 5.30×10^17 cm/s^2 .
B.) What is its vertical displacement during ...
1
vote
1answer
177 views
Monkey and tree - projectile motion
The famous scenario: A hunter is trying to shoot a Monkey hanging from a tree. However, this question doesn't mention the monkey jumping down from the tree or trying to escape. (The hunter uses a ...
0
votes
1answer
142 views
How do I find the magnitude and angle of the velocity?
I'm confused about the following problem.
A ball is shot from the ground into the air. At a height of $9.1\text{ m}$, its velocity is $v = (7.6\hat{\imath}+ 6.1\hat{\jmath})\text{m/s}$, with ...
0
votes
0answers
20 views
Movement of a ball on a curved ramp [duplicate]
Possible Duplicate:
What is a natural movement of a ball on a upward curve (the two arrow lines pointing upward) given no external force?
http://i47.tinypic.com/mt55s7.jpg
-See for image
...
0
votes
0answers
54 views
Accelerated motions of a car and a truck [closed]
A car and a truck start from rest at the same instant with the car initially at same distance behind the truck. The truck has constant acceleration of 3.4 m/s^2. The car overtakes the truck within the ...
0
votes
1answer
272 views
Kinetic energy in the center of mass
In a collision of a particle
of mass $m_1$ moving with speed $v_1$ with a stationary particle
of mass $m_2$ not all the original kinetic energy can be converted
into heat or internal energy. what ...
0
votes
2answers
166 views
Calculating vertical velocity component of a particle with mass, given the hit point of parabolic motion
Consider the following situation:
I have a particle with a given mass that at a given instant of time (let's say $t_{0}$) is placed at the system origin. The particle has a constant velocity ...
0
votes
0answers
78 views
Physics question motion in two dimensions? [closed]
A ball jumps from the plane and the ball has the acceleraion 500 m/s^2...the ball falls into the ground for 3 seconds..the speed of the plane is 500 m/s headed to east.Determine the position and the ...
0
votes
0answers
72 views
Downhill projectile question [closed]
I have to solve the following problem:
A hill is sloped downward at an angle $\theta$ with respect to the horizontal. A projectile of mass $m$ is fired with speed $v_0$ perpendicular to the hill. ...
3
votes
1answer
104 views
Is it possible to determine particles' velocities from their crossings on a ring?
2 particles are constrained to move in a ring. Both particles begin moving at $t=0$ from $p=0$, each particle moving in the opposite direction of the other. It is known that they are moving at ...
0
votes
2answers
193 views
What is the force of friction between two bodies given their masses and a force pulling them as a unit accross a surface?
Where a force of 200N pulls two blocks together(as one system) across a horizontal table top(µ=0.800)
$m_A$ = 5.00kg, $m_B$ = 10.0kg
Find the acceleration of the system.
Find f$_k$ between B and A
...
0
votes
2answers
136 views
Energy Question
Carl throws 100 g of Bohrium-262 (Half life: 0.10 seconds, undergoes alpha decay) to Sukhdeep with a initial horizontal velocity of 20.0 m/s at an initial height of 2.00 m above the ground. What is ...
0
votes
1answer
68 views
Minimum time required to reach a point [closed]
A police inspecter P is at point $ (\acute{x},\acute{y})$ and a thief X is at point $(x, y)$. X has a constant velocity $V_x\hat{i} + V_y\hat{j} $, where $\hat{i}$ and $\hat{j}$ are unit vectors in ...
0
votes
1answer
181 views
Solving inclined plane using diff. frame
I was trying to solve frictionless inclined plane problem using a diff. frame as shown in the figure, and can't figure out that acceleration along the plane = g.sin(Θ), but I think it should be = ...
0
votes
2answers
107 views
Negative sign of acceleration [closed]
This is the problem from our Physics textbook :
A player throws a ball upwards with an initial speed of 29.4 m s–1.
(a) Choose the x = 0 m and t = 0 s to be the location and time of the ball at ...
3
votes
1answer
303 views
How do I find the initial velocity in this problem?
An X-ray tube gives electrons constant acceleration over a distance of $20\text{ cm}$. If their final speed is $2.0\times 10^7\text{ m/s}$, what are the electrons' acceleration?
I know this ...
