The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of an object's speed and direction of motion (e.g. 60 km/h to the north). Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies.
Velocity is a physical vector quantity; both magnitude and direction are needed to define it. The scalar absolute value (magnitude) of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object has a changing velocity and is said to be undergoing an acceleration.
Homework Statement
A ball was thrown from a cliff, it reached to the ground after 2.5 seconds.
a) Find the height of the cliff.
b) Find the horizontal distance the ball reached.
Homework Equations
Δy = 2⋅g⋅t^2
Vfy = g⋅t
√(Vfy)^2+(Vfx)^2
Δx= Vx⋅t
The Attempt at a Solution
I've found Δy=30.6m...
Homework Statement
I don't remember exactly what the question was because it was on a quiz today. It said something along the lines of "a ladybug is on a turntable and begins to slip at .5 m/s. Find the coefficient of friction.
Homework Equations
Fc = (mv^2)/r
a = v^2/r
Ff = uFn
I think...
This is just a reality that I have stumbled upon that I'm sure was well-known, but I still found it interesting. I apologize if this is second-nature to physics experts.
I was responding to a post on a different thread that claimed you could make a tunnel around the Earth and if you sent a...
Homework Statement
A wave pulse on a string is given by D(x) = D[0][/SUB]/(x[2][/SUP]+a[2][/SUP]), where D0 is a constant with units of cm3 and a is a constant with units of meters.
a. If the wave moves along the string at a velocity of v in cm/s, what is the transverse velocity of particles...
Homework Statement
Given a graph (see below) containing the velocities of two stars with respect to the sun, I am asked to calculate the velocity of the centre of mass of a binary system. I am not given the mass of either star, nor the shape of the orbit nor the velocity of the centre of mass...
Homework Statement
Homework Equations
[/B]
T = inertia * alpha
The Attempt at a Solution
I'm not sure how the torque or angular velocity initially affects the time to speed, but it seems like the more angular velocity , then the quicker the engine would stop. I do know that more torque...
Homework Statement
A projectile is launched:
Horizontally, with an average displacement of 49 cm
Vertically, with an average displacement of 28 cm
At a 23 degree angle, with average displacement of 126 cm
Homework Equations
The Attempt at a Solution
I am sad to say I don't know how to do it...
I'm reading Weinberg's QFT volume 1. At the end of section 2.4 he is deriving the Inonu-Wigner contraction where he reduces the Poincaré group to the Euclidean one by taking the low velocity limit. In analyzing how the operators depend on velocity there are some I understand and some I don't.
I...
Homework Statement
A comet orbits the sun. It's position in polar coordinates is given by, $$r(\phi)=\frac{1.8r_0}{1+0.8\cos{\phi}},$$ where ##r_0## is the position at closest approach. Its velocity at this point is given by ##v_0##. Use the concept of angular momentum to find the following...
Hi there,
I'm struggling to distinguish why the following two equations are giving distinct answers, when the question explicitly states either could be used:
v=u+at
v^2=u^2+ad
when
v=12 m/s
u=0 m/s
a (average acceleration)= the unknown variable
d=24 m
t=4s
Theoretically, the two should...
Hi! I've found some excercices and expanation of Work always consider a constant velocity, this is a net Force equal to cero. Like spring or gravity excercices related against a force applied. Does this relation with constant velocity has some usefull explanation why? Should I always assume...
Homework Statement
In 1940, Emanuel Zachinni, one of a family of “human cannonball” performers, set a world record by traveling 53m. If he clears the 20 m tall ferris wheel (which is 25 m away from the cannon) by 10 m, how fast was he going at launch?
Homework Equations
range 53m...
I am trying to solve for Vy with given Vx. I know how to do this for the BLUE trajectory line, but I do not know how to solve this if there is an obstruction in the way (like the gray wall).
My givens are:
X1
X2
Y1
Y2
Vx
Gravity
Do I need to solve for the blue trajectory then adjust that for...
I read in several places that if, for example, a point particle exhibits uniform circular motion about the z-axis within an osculating plane not equal to the x,y plane, then the angular velocity still points along the z-axis, even though the angular momentum does not (it precesses about the...
I am solving a problem where I need to decide if an asteroids velocity is high enough to escape the planets gravitational pull. The way I did it was use conservation of energy and angular momentum to find an expression for the radial velocity and show that it remains positive as r tends to...
Homework Statement
In a physics lab, 0.30 kg puck A, moving at 5.0 m/s [W], undergoes a collision with a 0.40 kg puck B, which is initially at rest. Puck A moves at 4.2 m/s [W 30 N] . Find the final velocity of puck B.
Homework Equations
Conservation of momentum
Pythagorean theorum
The...
So I read these two other threads:
https://www.physicsforums.com/threads/relative-speed-of-two-cars.642873/
https://www.physicsforums.com/threads/two-cars-colliding.740948/
And gathered what I already thought was correct, that the relative velocities of two cars of equal mass crashing into...
Homework Statement
[/B]
A block travels in the positive x-direction with some velocity ##v_0##. It is subject to a drag force $$F(v)=-F_0e^{Kv},$$ where ##F_0,\,K## are positive constants. Find the point in time when the velocity of the block momentarily goes to zero. Find how far the block has...
Homework Statement
A particle of mass 7.3 × 10−5 g and charge 24 mC moves in a region of space where the electric field is uniform and is 6.3 N/C in the x direction and zero in the y and z direction. If the initial velocity of the particle is given by vy = 4.1 × 105 m/s, vx = vz = 0, what is...
Homework Statement
The water in the river moves southwest (45 degrees south of west) at 4 mi/h.
If a motorboat is traveling due east at 15 mi/h relative to the shore, determine the speed of the boat and its heading relative to the moving water.
Homework Equations
Vector summation
The Attempt...
Homework Statement
If the velocity v of the air in a boundary layer having a dynamic viscosity of
18x10-6 kg/ms is given in terms of the distance y from the surface by v = ay + by2
where a and b are constants, calculate the surface shear stress if at 1.5 mm from the surface the velocity is 75...
Hello. I have a question. If I am moving with velocity v for an observer O. If I experience and kind if time dilation and my time slows down with respect to observer O's time. But if my time slows down. For O I will be moving slowly in time. If time dilation is large enough. I will almost freeze...
Hi, i need help in deriving the velocity potential of a moving 2D cylinder (circle) in potential fluid.
The cylinder is moving in negative x direction U(t).
I can derive the velocity potential of fluid past a cylinder (cylinder is stationary, in which it is the scalar summation of uniform...
Homework Statement
Hello All,
I might be at best HS level physics understanding but I’m quick study and need guidance. I am in a debate with someone who thinks a body can be crushed to the point of dust. I’d like to know if a comparison can be made, basic ratio: Human crushed by a building at...
Hello!
I have some problems with geometry/kinematics, therefore i require in your help. :nb)
I need to estimate the velocity of manipulator's grapple.
I have found one solution (with the use of Jacobian's transformation), but i don't know, right it or wrong. Let's check together :wink:
Maybe...
Homework Statement
I am having trouble linking gravity to the radius of the Earth and angular velocity. I was using this as a solid method to confirm the equation for values of a different sort based on centripetal acceleration. When inputting the values though it does not add up and I cannot...
Hi, I appreciate any help. Thanks in advance!
Homework Statement
The image shows the top view of the set-up. Basically, it is a cylinder (resting on a horizontal plane) with two rods on either side attached in line with the centre of mass of the cylinder. Two pieces of string are then taped...
Homework Statement
A boy release ball A from height 5m from ground at the same time other boy throw ball B vertically upward to exactly strike ball A. When ball B released it was 1m from ground find minimum initial velocity of ball b. Given g=10m/s^2
a) 2m/s b) 3m/s c) 4m/s d) 5m/s
Homework...
Homework Statement
Consider the surface, S, in the xyz-space with the parametric representation: S: (, ) = [cos() , sin() , ] −1/2 ≤ ≤ 1/2 0 ≤ ≤ os().
The surface is placed in a fluid with the...
Homework Statement
Estimate the velocity of thermal neutrons at 25 degrees celcius
Homework EquationsThe Attempt at a Solution
I attempted to use KE=0.5mv^2 but I realized that I didn't know the Kinetic energy
Can anyone tell me the difference between concept of relative velocity and effective velocity and when to use the concept of relative velocity?
For example, if a guy throws a ball from a moving object at an angle theta it undergoes projectile motion we write horizontal velocity as...
Homework Statement
During a short interval of time the speed v in m/s of an automobile is given by v = at^3 + bt^4 , where the time t is in seconds. The units of a and b are respectively:
(a) m⋅s^2 ; m⋅s^4 (b) s^3/m; s^4/m (c) m/s^2 ; m/s^3 (d) m/s^3 ; m/s^4 (e) m/s^4 ; m/s^5
Homework...
When calculating the center of mass for an MD simulation, I've seen a few codes that subtract the average velocity from each atoms velocity. I think the reasoning behind this is that you want the velocity of center of mass for the simulation to be zero, which I understand, but I don't understand...
Hi there,
prob a simple question for you physics gurus, but this application is for a race car, and question relates to air flow velocity through a pipe, in particular exhaust and intake.
Now, my thinking for the exhaust (push) is that by going from a small diameter to a large diameter will...
1 What must your car’s $V_{av}$ be in order to travel $\textbf{235 km}$ in $\textbf{2.75 h}$
\begin{align*}\displaystyle
V_{av}&=235km/2.75h \, km/h \\
&=\color{red}{85.45 \, km/h}
\end{align*}
2 A particle at $t_1 =–2.0 s$ is at $x_1 = 4.8 cm$ and at $t_2 = 4.5 s$ is at...
I am making a physics simulator and this problem is tricky. You have two freely moving objects with known masses and velocities in a frictionless environment. The first object is a ball and the second is a pipe. They are moving toward each other. I need to know what formulas are used to simulate...
Hi guys!
My question is about the diffusion coefficient of the mixture of gases. Consider two gases in thermal equilibrium (Maxwell velocity distribution) having different densities n1 and n2. Let's suppose that the molecules are rigid spheres with diameters d1 and d2 and masses M and m...
Homework Statement
A hockey player hits a slap shot, exerting a constant force on a 3.06 kg puck for 0.06 seconds. What is the change in momentum of the puck?
Homework Equations
Impulse = Mass x (Change in velocity) = Force x time
(I think that’s all needed? Most likely missing one.)
The...
A problem I struggle to conceptualise as I have began leanring about relativity and seek your guidance and knowledge on:
Consider a stationary observer at point A. Relative to the observer there is a train traveling at -0.6c. A passenger on board the train has a particle gun, and fires it in...
Imagine, There's a ball in deep space traveling with a constant velocity of 25m/s and is having mass 25kg.
Now as I said, ball is traveling with a constant velocity that simply means acceleration=0 and now if we calculate the force with F=ma we will end up with 0. But if that ball collide with a...
Homework Statement
Hi everyone,
8th grade physics teacher here.
We are doing a handout where we have to identify time-velocity graphs with descriptions. Can you help me with this one?
https://imgur.com/a/vEIkg
A) The velocity is increasing at a uniform rate.
B) The velocity is decreasing at...
Homework Statement
14.10 Solve Prob. 12.47 by the work-energy method
12.47 When the 1.8-kg block is in the position shown, the attached spring is
undeformed. If the block is released from rest in this position, determine its velocity
when it hits the floor
Homework EquationsThe Attempt...
Homework Statement
A spring with an elastic constant of 120 N/m is compressed 0.2 m, then launches a block of mass 0.5 kg on a table with friction 0.49, and it travels 0.9 m before stopping. If the block is then released at the edge of a table top 1.2 m above the ground, how far will the block...
Homework Statement
This problem showed up in my final review packet, and I /think/ it should be basic kinematics, but I don't even know how to approach it with the second half of it.
An object moves according to the equation x = vt + ke^(bt), where k, v, and b are constants, x represents...
Hi everyone,
Me and a friend discussed a problem relating to a rotating reference frame, and somehow got to this question which we can't fully figure out, or maybe we are missing something. so, here goes:
On Earth's equator, our tangential velocity is ~1700 km/hr. A satellite orbiting right...
Homework Statement
Homework Equations
change in momentum = m1v1 = m1v1+m2v2
center of mass = m1x + m2x / (total mass)
The Attempt at a Solution
m1v1= m2v2 + m3v3
m1 = 2
v1 = 4
m2 = m1 divided by 2
m3 = m3 divided by 2[/B]
2*4 = 1*12 + 1v3
v3 = -4
v3= -4? in the x directioncenter of mass...
Hi, I engage in physics as a hobby, and I'm not extremely familiar with things reaching into calculus levels of math. That said, how would I find the velocity of a bullet at a given time or distance, taking wind/humidity/etc. out of the equation?
I know the muzzle velocity only applies to the...
$\tiny{UP 2.1}$
$\textsf{A rocket carrying a satellite is accelerating straight up from the Earth's surface}$
$\textsf{At 1.15 after liftoff, the rocket clears the top of its launch platform, 63m above the ground.}$
$\textsf{After an additional 4.75s it is 1.00km above the ground.}$...
An object, moving in a straight line, has a velocity of 5.0 m/s at time t = 0. From t = 0 to t = 5 s its acceleration is 2.5 m/s2 , while from t = 5 to t = 11 s its acceleration is - 0.1 m/s2 . Over the time interval t = 5 s to t = 11 s its average velocity is: (a) 15.0 m/s (b) 12.5 m/s (c) 17.2...