Kinematics Definition and 1000 Threads

Please look at attached picture. Why did my teacher assume that vf does not change upon landing in the last sub-question? This makes no sense to me. Is there such a way that the skier can change direction of vf without changing the magnitude of it? Otherwise, the skier will collide in an...

Homework Statement A projectile is fired at a stationary vehicle. If the initial separation was 200m and the projectile traveled at a constant 75 m/s, find the acceleration the vehicle would need for a passenger to be able to reach out and calmly pull the projectile into the vehicle. (Assume...

Homework Statement A particle has initial velocity and constant acceleration. If its velocity after certain time is v then what will its displacement be in twice of that time? Homework Equations The Attempt at a Solution Im thinking about using one of the classic kinematics...

Homework Statement A sprinter reaches his top speed of 11m/s in t seconds from rest with essentially constant acceleration. If the maintains this speed once reached and covers the 100m distance in 11.5s, Find: a) the time it took to accelerate. b) his acceleration until he reaches...

Homework Statement A small steel ball of mass .0283kg is placed on the end of a plunger of length .0051m attached to a spring 1.88m above the ground. The spring is pre-compressed .0011m and has a spring constant of 177 N/m. The plunger is then angled on a ramp 45° above the horizontal, and is...

Kinematics -- particle acceleration and distance travelled Homework Statement A particle moving at 10 m/s reverses its direction to move at 20 m/s in the opposite direction. If its acceleration is -10 m/s2, what is the total distance that it travels? A) 15 m B) 20 m C) 25 m D) 30...

Kinematics help -- object is dropped from a height h Homework Statement An object is dropped from a height h and strikes the ground with a velocity v. If the object is dropped from a height of 2h, which of the following represents its velocity when it strikes the ground? A) v B) 1.4v...

Hi guys, having some trouble with this question as I cannot see where I am going wrong. Very simple question but I must be misunderstanding something. Homework Statement The following table shows how the velocity of a car varied with time: Velocity (km/h) 0 19 35 48...

When you want to get velocity from accelleration i have been told you integrate. Howver v=at and so surley you can just multiply each term in the accelleratin expression by t. ie: a=4-0.2t Surley you can just: v=(4-0.2t)t v=4t-0.2t2

In the sport of luge, a competitor slides on a sled down a 500-m long straight ice track inclined at 20o to the horizontal. Her initial speed is 2.0 m s-1. The coefficient of dynamic friction between the sled and the ice is 0.050. Neglect air resistance. What is her acceleration? What is her...

Homework Statement An object thrown up from a cliff 10 m/s reaches a velocity of 20 m/s [down] as it lands. If acceleration due to gravity is 9.8 m/s2, what is the object's displacement? How long did it take for the object to land from the time it was thrown? Homework Equations I'm not...

Homework Statement A stone is thrown with a velocity v_{0} at an angle \alpha to the horizontal (see image) from a step of height H. Calculate the x coordinate x_{1} of the point where the stone hits the ground. Homework Equations x(t) = u_{x}t + x_{0} y(t) = u_{y}t +...

Homework Statement A ball is thrown vertically upward from ground level with an initial velocity V0. The ball rises to a height, h, then lands on the roof of a building of height 1/2h. The entire motion requires 10s. Find the height, h, and the initial velocity, V0. Homework Equations...

Homework Statement A 3.50kg block of wood is at rest on a 1.75-m high fencepost. When a 12.0g bullet is fired horizontally into the block, the block topples off the post and lands 1.25m away. What was the speed of the bullet immediately before the collision?The attempt at a solution d=1/2at^2...

Hi everyone; I'm a ME student who just finished Dynamics course and I did really good. I've finished also statics course it was not easy, I faced some difficulties. So, the next semester I'll do "Kinematics and dynamics of machinery" course and I'm so worry. Is it real that Kinematics is...

Kinematics -- projectile motion -- time to maximum height? Homework Statement The nozzle of a fire hose discharges water at a speed of 10 m/s. The nozzle is aimed straight up. How long does it take for a water drop to reach its maximum height? Start with translating the question: vi= 10 m/s...

Kinematics -- How fast does the car stop? Homework Statement A car is moving with a speed of 32.0 m/s. The driver sees an accident ahead and slams on the brakes, giving the car an acceleration of -3.50 m/s2. How far does the car travel after the driver put on the brakes before it comes to a...

Homework Statement Mortar crew is near the top of a steep hill. They have a mortar. They angle this mortar at an angle of \theta = 65° . The crew fires a shell at a muzzle velocity of 228 ft/sec (69.5 m/s). How far down the hill does the shell strike if the hill subtends an angle of \phi =...

2D Kinematics -- 2 rocks off a bridge Homework Statement Heather and Jerry are standing on a bridge 60m above a river. Heather throws a rock straight down with a speed of 14m/s . Jerry, at exactly the same instant of time, throws a rock straight up with the same speed. Ignore air...

A car is stopped at a traffic light in the moment in which a truck which has a constant speed of 50 Km/h passes throught a trafic light light eats and passes the car 10.s later the traffic light changes and the car accelerates to 2 m/s2 for 15 sec then which, it continuous your travel at...

Kinematics -- centrifuging a solution with bacteria Homework Statement In the lab, we have to separate the bacteria from the solution by centrifuging the solution with bacteria. Because the bacteria are more massive than the media molecules, they settle to the bottom of the container. For...

Homework Statement Two balls are thrown upwards from the same spot 1.15 seconds apart. The first ball had an initial velocity of 15.0 m/s and the second was 12.0 m/s. At what time do they collide? 2. The attempt at a solution a = first ball b= second ball For them to collide, their height...

Problem goes like this.. body falls toward a planet with acceleration of -g0*R^2/s^2. where R is the radius of planet 4000 miles, g0 is 30 ft/s^2, s is the distance of the body from the planets center. the initial distance of the body from the surface is 400 miles. find the impact velocity...

Homework Statement I currently have a few problems I am working on for my calculus based physics class. I'm duel enrolling in both calc based physics and calc at this moment. |||The first problem is The figure (figure 1) shows the motion diagram, made at two frames of film per second, of a...

Hey, so I've been having some problems with Kinematics in reviewing for my finals next week! One question in particular I need help with, because I don't know how to solve it, and I am very bad at conveying my solutions on tests. Can anyone give me a hand? The question is : a basketball...

Question The wheel of a car has radius 0.2m and initially rotates at 120 rpm. In the next minute it makes 90 revolutions What is the cars angular acceleration?Attempt So I tried to get the final angular velocity and couldn't and have tried multiple times with the angular kinematics equations...

Homework Statement http://postimg.org/image/bh4tzmd4l/ Can someone explain to me what "acceleration of the truck relative to the crate means"? What should I do first in trying to solve this?

Say you have a v-t diagram for the motion of a particle in one dimension where the velocity is positive at first and then negative later. If you integrate and get zero, why doesn't that mean that the particle started moving and then came back to the origin?

Homework Statement A point begins at rest at x = 0 and accelerates at 1.09 m/s^2 to the right for 10 s. It then continues at constant velocity of 10.9 m/s for 8 more seconds. In the third phase of its motion, it decelerates at 5 m/s^2 and is observed to be passing again through the origin when...

Ok so I have this problem which is most likely easy to all of you. The problem says that the first 10 meters of the 100 meter are covered in the first 2 seconds by a sprinter who starts from rest and accelerates with a constant acceleration. The remaining 90 meters are run with the same velocity...

A subway train rounds an unbanked curve at 67km/h. A passenger, hanging onto a strap notices an adjacent strap is unused and makes an angle of 15° to the vertical. What is the radius of the turn? Relation of sines, opposite and hypotenuse of a right triangle. Opposite...

I'm about to ask derivation of dilation time in terms of Special Relativity. I saw explanations in Introduction to Classical Mechanics by David Morin that dilation time is formed by assumption that light speed is absolute refers to all inertial reference. He derived it by comparing 2...

This problem is originally from Wopho and its goal is to describe the trajectory of a point mass charge around a dipole. http://img18.imageshack.us/img18/2676/fvac.png First we have to calculate the radial and tangential electric fields made by the dipole (this I've done as well) but...

Question: A cannon, located ##60.0 m## from the base of a vertical ##25.0 m## tall cliff, shoots a ##15 kg## shell at ##43.0°## above the horizontal toward the cliff. What must the minimum muzzle velocity be for the shell to clear the top of the cliff? I have attempted a solution that I'm...

Hi everyone, I would really appreciate any advice on how to go about solving the following problem. I'm supposed to investigate it in a report. Homework Statement A paratrooper who jumps out of an aircraft moving in horizontal flight initially has the same horizontal velocity as the aircraft...

the 14 in. spring is compressed to an 8 in length, where it is released from rest and accelerates black A. the acceleration has an initial value of 400ft/sec^2 and then decreases linearly with the x-movement of the black, reaching zero when the spring regains its original 14 in. length...

Ball 1 is launched with an initial vertical velocity v1=160 ft/sec. Three seconds later, ball 2 is launched with an initial velocity v2. determine v2 if the balls are to collide at an altitude of 300ft. not sure where I am going wrong, do I have my limits...

Homework Statement Here is the question.. Figure P2.35 (A link to the image is posted) represents part of the performance data of a car owned by a proud physics student. (a) Calculate the total distance traveled by computing the area under the red-brown graph line. (b) What distance does the...

Homework Statement You're a consultant on a movie set and the producer wants a car to drop so that it crosses the camera's field of view in time Δt. The field of view has height h. Derive an expression for the height above the top of the field of view from which the car should be released...

Homework Statement An object starts moving in a straight line from position xi, at time t =0, with velocity vi. Its acceleration is given by a = ai + bt, where ai and b are constant. Find expressions for a)instantaneous velocity b) position as functions of time. Homework Equations...

Homework Statement A police radar's effective range is 1km and your radar detector's range is 1.9km. You're going at 110kmh^-1 in a 70kmh^-1 zone when the detector beeps. At what rate must negatively accelerate to avoid a speeding ticket? Homework Equations none The Attempt at a...

Homework Statement A balloon takes 0.22s to cross a 1.3m high window. From what height above was it dropped? Homework Equations None. The Attempt at a Solution

Kinematics motion -- Dancers pausing at top of their leap Homework Statement Ice skaters, ballet dancers, and basket ball players executing vertical leaps often give the illusion of "hanging" almost motionless near the top of the leap. To see why this is, consider a leap to maximum height, h...

Hi, I have an basic kinematics problem I can't seem to grasp -- hopefully someone can shed some light on it for me? The acceleration, a, of an object is equal to a=s, where s is the distance from the start position. Sketch a graph representing velocity against distance, s, for the...

Everytime I go into the homework questions forum and look at threads started by people it always makes me laugh what threads have so many comments. In the introductory physics forum when it's a question on kinematics, there's always like 10 people that answer. As soon as there's something about...

Kinematics motion -- Given position, find velocity and acceleration Homework Statement A particle's position as a function of time is given by xf = xi . sin wt, where xi and w are constants. a) Find expressions for velocity and acceleration. b) What are the maximum values of velocity...

Homework Statement Consider an object traversing a distance L, part of the way at speed v1 and the rest of the way at speed v2. Find expressions for the average speeds when the object moves at eac of the two speeds. a) for half the total time b) for half the distance Homework...

Homework Statement A book is toss into your dorm room, just clearing a windowsill 4.2m above ground. a)If the book leaves your hand 1.5m above ground, how fast must it be going to clear the sill? b)How long after it leaves your hand will it hit the floor, 0.87m below the windowsill...

Homework Statement At the buzzer, a basketball player shoots a desperation shot. She is 14m from the basket and the ball leaves her hands exactly 1.4m below the rim. She throws the ball at 18m/s. Can she make the shot? (Solve for necessary angle) Homework Equations r2y = r1y + v1y(t2)...

Homework Statement You're an investigator for the National Transportation safety board, examining a subway accident in which a train going at 80kmh^-1 collided with a slower train traveling in the same direction at 25kmh^-1. Your job is to determine the relative speed of the collision to help...