Constant velocity Definition and 199 Threads

Homework Statement Another canoe question! A canoe is headed directly across a river that is 200 m wide. Instead of moving with a constant velocity, the canoe moves with a constant acceleration of 4.0 x 10-2 m/s2. If the river is flowing with a constant velocity of 2.0 m/s, how long...

A crane lifts the 18,000-kg steel hull of a ship out of the water at constant velocity. (A) Determine the tension in the crane’s cable when the hull is submerged in the water. (B) Find the tension when the hull is completely out of the water. I would have thought that B would just be...

Hello guys! I'm trying to model a simple model of a driving shaft connected to a rear axle. The axles are connected to each other by a pinion and crown gear. However this isn't any problem to model. My problem is that I want the driving shaft to rotate at a constant angular speed and then...

Homework Statement Calculate the torque, t about origin that must be applied to a particle for it to maintain a constant speed v along a cardiod. Homework Equations t = r x f a = (r_dot dot - r*Θ_dot ^2) r_hat + (r*Θ_dot dot + 2 r_dot * theta_dot) theta_hat The Attempt at a...

I had an interesting debate with a friend of mine recently. They claim that a stationary object (we are JUST talking about our reference frame here) observed by us has a constant velocity, even if it is 0. However, I claim that since velocity is a vector quantity, which requires both magnitude...

I lower an object at constant velocity. What is the sign of the total work done on the block? What is the sign of the work done by gravity on the block? What is the sign of the work done by my hand on the block? What is the sign of the work done by the block on my hand? I know that...

Homework Statement An elevator goes up 180 m by first accelerating at a constant rate of 1.0 m/s2, then staying at a constant speed of 9 m/s and then decelerating at a constant rate of -­‐‑1.0 m/s2. How much time does it take the elevator to go from bottom to top? so i know that d = 180m...

Homework Statement A 15 kg crate rests on the floor. The coefficient of kinetic friction between the crate and the floor is 0.28. How much horizontal force is needed to slide the crate across the floor at a constant speed? Homework Equations Fnet=ma The Attempt at a Solution F=MN...

Homework Statement True or False The stresses on an object traveling at constant velocity are the same as the stresses on an object.at rest. Homework Equations F = m*a The Attempt at a Solution For both an object at constant velocity and an object at rest the acceleration is...

Homework Statement Which of the following is NOT true about an object having constant velocity? Select one: a. It has constant speed b. It is moving in a steady/fixed direction c. It has constant acceleration d. It might be at rest e. It might have a fixed position Homework...

Homework Statement Lifting an object from point A to point B with a tension T in the string at constant velocity. What is the work done on the object? Homework Equations Work=Force x distance The Attempt at a Solution Net force = T - mg Net F = 0 because acceleration = 0 T =...

Homework Statement A cable lifts a 1200 kg elevator at a constant velocity for a distance of 35 m. What is the work done by (a) the tension in the cable and (b) the elevator's weight? Homework Equations W = fscos(theta) The Attempt at a Solution okay i already know the...

Homework Statement a 3 kg block is placed on an incline of 37 degrees with respect to the horizontal. The coefficient of static friction is 0.333, and the coefficient of kinetic friction is 0.167. What type of motion, constant or acceleration, will be observed? Homework Equations μ =...

Hi there, I'm trying to create a computer model which takes into account output power in a car due to acceleration, drag and rolling resistance. The car will be accelerating for a set amount of time and I am able to model the power required for this with respect to time, as well as the power...

I've come to the conclusion that i don't understand at all the concept behind inertia. How can we know when an object stays at rest or at constant velocity? (take for example a girl in a rope. She would tighten her grip on the rope until the tension balances the force of gravity (assume rope is...

Oops! That title should read constant *speed.* 1. An object with mass m starts at rest at height h. It slides down a frictionless incline. At the bottom, it enters a vertical circular loop-the-loop of radius r. It just touches the track at the top of the loop. What is h in terms of m...

"The geodesics in R n are the straight lines parametrized by constant velocity". This can be proved with the geodesic equation: \ddot{x^a} + \Gamma^a_{bc} \dot{x^b} \dot{x^c}=0 Locally we can find a coordinate system such that \Gamma =0 , and thus: \ddot{x^a} =0 So along a geodesic at some...

Homework Statement "You carry your 14.0 kg bag of textbooks horizontally 1.8 m above the ground, at constant velocity for a distance of 25 m. Ignore wind resistance. How much work do you do on the bag in the process?" Homework Equations W=Fd F=ma The Attempt at a Solution If work...

1. Supose a car, going at a constant velocity, decelerates to a stop by pressing the brakes. Is the friction used to stop the car kinetic or static friction? PLEASE explain why. My teacher said the answer was static friction, but I don't understand this. Since the car is already moving and the...

Homework Statement A vacationer gets into his out-board motorboat and leaves a dock on a river bank for a day of fishing. Just as he turns upstream, he hears a splash but pays no attention and continues cruising at normal speed. 30.0 minutes later he realizes that his watertight lunchbox is...

Homework Statement A building is 320 meters tall. An elevator accelerates uniformly for 30 meters, travels at a constant rate for 260 meters, then decelerates uniformly for the last 30 meters. The total time is 90 seconds. What is the velocity for the middle 260 meters? Homework...

Hi All, A question to calculate the speed at constant velocity during a Trapezoid move. An object moves from standstill at a known acceleration (1m/s/s) to a constant velocity (unknown) for a period (unknown) and then decelerates at a known deceleration (2m/s/s) to standstill. The total...

According to my level of knowledge,my point of view regarding an object moving with constant velocity is that there should be a force acting on it for its continuous motion(eg:when riding bicycle we give a force continuously).But the theory says it is not.can anyone explain?

Homework Statement Starting from rest, an elevator accelerates uniformly between the 1st and 2nd floors, and decelerates uniformly between the 5th and 6th floors, coming to a stop at the 6th floor. Between the 2nd and 5th floors, the elevator covers the 6 meter distance between each two...

Homework Statement A man is pushing a 75 kg crate at constant velocity a distance of 12 m across a warehouse. He is pushing with a force of 225 N at an angle of 15° down from the horizontal. The coefficient of friction between the crate and the floor is 0.24. How much work did the man do...

I have two examples.Terminal velocity-When the forces are balanced,the person continues to fall down at a constant velocity. Holding a Box-When the forces are balanced,the box stays at rest. A question about power in my textbook is:A crane lifts a box of weight 100N up at a constant velocity.The...

This is all hypothetical. Say that I build a machine something like an air-hockey table with pucks that move on it. Each puck has a magnet in it such that the pucks attract each other Now imagine that the puck can only go at one speed. no faster and no slower. If two pucks attract...

If a car with no acceleration, only velocity, hits my spring with a spring constant K What will be the deformation in string? How do I calculate the force from impact while acceleration is equal to 0?

This is just a very simple conceptual question. Say that someone is going down an escalator at a constant velocity. They are losing GPE, but not gaining any KE. So where is this potential energy going? Same with going up, they're gaining GPE, but not losing any KE. On a similar note, say...

Homework Statement At what speed would a heavy object hit the ground if it was lifted vertically from the ground at a constant speed of 1.2 m/s for 2.5s and then dropped? Homework Equations Ep= mgh Ek= 1/2 mv^2 The Attempt at a Solution Im not sure how to do this. Do i find Ek 1/2mv^2...

Constant velocity problem, where does increase in energy come from? Let's say that an object is being pushed with a constant force across a surface, and it is moving with a constant velocity. We can use Newton's second law to show that the force of friction is equal to the force of the push...

Homework Statement Could you please clarify the confusion I have about potential energy? Consider an object being raised from the Earth's surface upwards at a constant velocity. Is the potential energy increasing while it is moving upwards at a constant velocity?Homework Equations The Attempt...

https://www.khanacademy.org/science/physics/work-and-energy/work-and-energy-tutorial/v/work-and-energy--part-2 I was watching a video at Khan Academy on Work & Energy (link above). At 2:50, he describes a situation with an elevator doing work against gravity. My question is pretty simple: If...

Homework Statement Five dogs, each having a mass of 30kg, pull a 250kg sled horizontally across the snow (coefficient of kinetic friction = 0.14). How much force must each dog exert in order to move the sled at a constant velocity? Homework Equations Force of kinetic friction =...

This question might seem strange or dumb.. At least it does in my mind, however I phrase it.. Anyway, I'm wondering about the reasons for acceleration being felt and constant velocity not being felt by a human body or other object. If you're sitting in a train or a car and it accelerates...

Homework Statement 2 equal masses (massA, massB) are raised up a pulley, at a constant velocity. massB has a velocity twice as fast as massA. What is the force acting on these 2 masses? Homework Equations The Attempt at a Solution If it is a constant velocity, the upwards force...

i have to design an actuation system which will change the angle with which the power is transmitted through a motor,the range of angle is about,--35 to +35,w.r.t to the vertical,what should i use,a u joint or a velocity joint?there is a predefined load on the shaft(bending + torsional),what...

Homework Statement Movers must push a piano onto a truck, the bed of which is a height 1.73 m above the ground. To do this they will use a frictionless ramp. If the piano has a mass of 1635.0 kg and the movers push it up the slope at a constant velocity, how much work do they need to do on...

Homework Statement Lifting a 20lb bucket of sand a distance of 100 ft at a rate of 2ft/s. I would assume: [W=F*d] = [W = MA*d] = [W = M(v/t)*d] and at a constant velocity: rate of v/t=0 so [W = M(0)*d] = [W = 0*d] = [W = 0] However, a video online shows that you'd take 20lb*100 ft...

If you push on a crate with a force of 100 N and it slides at constant velocity, how much is the friction acting on the crate? Consider a crate being pushed horizontally across a factory floor. If it moves at a steady speed in a straight - line path, it is in dynamic equilibrium. This tells...

1) In the following four scenarios, determine the sign of the ball’s velocity and acceleration. Up is positive. The ball is thrown straight up. (Velocity is positive, Acceleration is negative) Up is positive. The ball is dropped straight down. (Velocity is negative, Acceleration is negative)...

In this question, the horizontal unit vectors i and j are directed due east and north respectively. A coastguard station O monitors the movements of ships in a channel. At noon, the station's radar records two ships moving with constant speed. Ship A is at the point with position vector...

Homework Statement An object starts at rest and accelerates at 2.5 m/s^2 for 12 seconds. It then moves at a constant velocity for 5.0 seconds and then slows down uniformly at 1.5 m/s^2 until it stops. Calculate: a) the constant velocity b) the time taken for deceleration c) the total...

You are pushing a refrigerator across the floor of your kitchen. You exert a horizontal force of 291N for 7.5s, during which time the refrigerator moves a distance of 2.7m at constant velocity. (a) What is the total work (by all forces) done on the refrigerator? (b) What is the work done...

I need help solving this problem. To be clear, I AM NOT LOOKING FOR THE ANSWER...just need some hints as to HOW to go about solving. I've tried several paths/steps and I keep going in circles. Can someone please help me get started on a path? Person A left Town X at 10:18 am. He walked at...

The fields of a moving point charge can be constructed from the Lienard-Wiechert potentials. However could one not just consider a point charge at rest in a frame S' and transform the relevant quantities such as A^{\mu} back to S and then deduce the fields from here. Should not the the two...

Problem Statement: I'm having some trouble understanding how to write charge densities using delta functions, particularly when they involve geometries other than Cartesian. So I have a disk moving with velocity v (along the z-axis) that has total charge Q, and I'm trying to write ρ(x,t) so that...

Homework Statement 3 clocks at to A clock on Earth B clock above Earth 4.66 * 1014 meters C clock above Earth 3.30 * 1013 meters B accelerates to .6 c and arrives at Earth when Earth clock reads 2.6 *106 sec = 30 days With velocity 1.8 *10^8 m/sec with gamma = .8 B clock reads 2.07 *...

It's been a while since I've done any work-energy questions, and I just noticed how vague some questions could be (or maybe I don't understand it that well). Anyway, suppose I have a box moving down an incline where the only forces acting on it are its weight, the normal force, and friction...

I got a 30kg rock in space, no gravity, no friction. It is traveling at a CONSTANT speed of 100m/s. According Newton's second law, There should be NO force because there is NO acceleration. But I know if it hits another object it will either move the object or put a hole in it so I know there is...