Kinematics problem Definition and 279 Threads

Homework Statement An owl accidentally drops a mouse it was carrying while flying horizontally at a speed of 5 m/s. The mouse drops to the ground 10m below. What is the mouse's impact velocity? Give the answer as a magnitude and clearly defined angle. As of right now I'm not even sure how...

Homework Statement Directly from my homework. One of the fastest recorded pitches in major-league baseball, thrown by Nolan Ryan in 1974, was clocked at 100.8 mi/hr. If a pitch were thrown horizontally with this velocity, how far would the ball fall vertically by the time it reached 61.2 ft...

You drive at a constant speed of v1 toward the stopped dragster, not slowing down in the face of the imminent collision. The dragster driver sees you coming but waits until the last instant to put down the hammer, accelerating from the starting line at constant acceleration, a. Let the time at...

Homework Statement In a historical movie, two knights on horseback start from rest 62 m apart and ride directly toward each other to do battle. Sir George's accleration has a magnitude of 0.21 m/s2, while Sir Alfred's has a magnitude of 0.26 m/s2. How far from Sir George's starting point do...

Homework Statement Speedy Sue, driving at 30.0m/s, enters a one-lane tunnel. She then observes a slow-moving van 155m ahead traveling at 5.00m/s. Sue applies her brakes but can only accelerate at -2.00m/s^2 because the road is wet. Will there be a collision? State how you decide. If yes...

A chain, total length h meters long, is sitting on a table. C meters hang down from the table. The chain is let go from rest at time t=0 . The table is frictionless. Find the equation of motion, x(t) Hint: Second order differential equations that can be reduced to cosh if x is defined...

A fly falps its wings 1000 times per second. This means that the wing tip is accelerated from rest to a maximum velocity in 0.0025 seconds. If the wing tip travels 2mm in this time: a) What is the average acceleration of the wing tip? what i got is i converted 2mm to meters then multiplied...

1. A wrecking ball is hanging at rest from a crane when suddenly the cable breaks. The time it takes for the ball to fall halfway to the ground is 1.2 seconds. Find the time it takes for the ball to fall from rest all the way to ground 2. Vf=Vo-gt, Vf^2=Vo^2-2g(delta y), Yf=Yo+Vot-1/2gt^2 3. I...

Homework Statement In reaching her destination, a backpacker walks with an average velocity of 1.36 m/s, due west. This average velocity results, because she hikes for 5.18 km with an average velocity of 2.05 m/s due west, turns around, and hikes with an average velocity of 0.699 m/s due east...

A particle moves along a straight line with accel. a = 2\sqrt{v} where v = \frac{dx}{dt} is the velocity. At t = 2s, the particle is located at x= (64/3)m with velocity v = 16m/s. Find the location and acceleration at time t = 3s (hint: integrate) Now, if the differential equation is dv/dt =...

Homework Statement Consider a frictionless sphere of radius r=5.0m that is fixed to the ground and a small block of mass m=1.0 kg that is nudged slightly from the very top. This takes place on the surface of the Earth. Find the location on the ground where the block lands by following the...

This is doing my head in. It should be really simple, but I just can't work out the reasons why. I have a particle of 50g that drops from rest. It drops 1m in 12s. I then have to find the final velocity of the particle after this 12s. Using v = u + at I get v=12g Using h = (u+v)t/2 I...

Hi everyone, any help you could give me I would appreciate. Homework Statement A 10 kg projectile is fired vertically upward from the ground, with an initial velocity of 50 m/s. Determine the maximum height to which it will travel if (a) atmospheric resistance is neglected, and (b) if...

Homework Statement Thelma and Louise's car falls off the edge of the Grand Canyon and plunges to certain catastrophe below. The depth of the canyon at this point is 500 m. (Assume it drops off) A) How long will it take the vehicle to impact the canyone bottom? B) What will the...

Homework Statement A student throws a stone vertically downward with an initial velocity of 5.0 m/s from the top of a 165 m building. How far does the stone travel during its 4th second of travel? Homework Equations d= vit + 1/2at2 The Attempt at a Solution Vi = -5.0 m/s t =...

Homework Statement Alvin races Ophelia to Physics class. Alvin has a headstar of 13m and travels at a constant speed of 7m/s. Phelia is initially traveling at 1.2m/s but then begins to accelerate at 1.5m/s2 until she reaches the physics classroom 100m away from her. Who wins the race? when...

What is the angle if the reach is three (3) times the maximum height. I put both of the reach and max height formula together to isolate theta p=\frac{V_{0}^{2}sin(2\theta)}{-g} and h_{max}=\frac{V_{0}^{2}sin^{2}\theta}{-2g} At the end it gave me this: \frac{3sin\theta}{2}=2cos\theta Am I...

A car that weighs 12000.0 N is initially moving at a speed of 30.0 km/hr when the brakes are applied and the car is brought to a stop in 4.1 s. Find the magnitude of the force that stops the car, assuming it is constant. This is the wrong problem ^^^ A 6.70 kg penguin runs onto a huge...

Homework Statement This problem has really been bugging me, and i can't seem to figure it out. Heres the question: Nicole throws a ball straight up. Chad watches the ball from a window 5.90 m above the point where Nicole released it. The ball passes Chad on the way up, and it has a speed...

A boat takes 2.6 hours to travel 28.43 km down a river, then 5.5 hours to return. How fast is the river flowing? So we want to find the velocity the river has. I'm not sure I even started this right. First I converted 2.6 hours to seconds = 9360 s Then 5.5 hours to seconds = 19800 s...

I just need help getting started with this question. A 1350.0 kg weather rocket is launched straight up. The rocket motor provides a constant acceleration for 10.2 s, then the motor stops. The rocket altitude 26.9 s after launch is 2210.0 m. You can ignore any effects of air resistance...

Hi, I am having some trouble with this simple kinematics problem. Here it is: A skier is gliding along at 2.91 m/s on horizontal, frictionless snow. He suddenly starts down a 22° incline. His speed at the bottom is 12.18 m/s. The first question asks for the length of the incline, which...

Homework Statement So the problem says that three turtles starts to move each from a vertice of a equilateral triangle with a constant velocity v as shown in the pic. They move towards each other ( the first one moves towards the second the second towars the third and so on ). It asks: When...

Q: The average alcohol-free driver requires about 0.8 s to apply the brakes after seeing an emergency. Calculate the distance traveled after seeing the emergency before applying the brakes. with the question, the given speed is 17 m/s and t = 0.8. at first, i used d =vt equation to find the...

Homework Statement At the base of a frictionless icy hill that rises at 28.0 degrees above the horizontal, a toboggan has a speed of 12.0m/s toward the hill. How high vertically above the base will it go before stopping? Homework Equations height = [(v*sin (angle))^2] / (2g) The...

a car is moving at 56km/h when a deer jumps onto the road 65m ahead. after a reaction time of t seconds, the driver applies the brakes to produce an acceleration of -3.0m/s^2. what is the maximum reaction time allowed if the car is to avoid hitting the deer?

Homework Statement A car moving with a constant acceleration covered the distance between two points 56.1 m apart in 5.44s. Its speed as it passes the second point was 14.2m/s. (a) what was the speed at the first point? (b) What was the acceleration?. (c) At what prior distance from the...

Homework Statement A rocket powered sledge accelerates at 35ms-2 and takes 1.6s to pass through a 60m section of a test track. Find the speed at which it entered the section what was its speed when it left? Homework Equations I think this is the equation to use x=ut + 1/2at2 and...

Homework Statement A skier is going 8.2m/s when she falls and starts sliding down the ski run. After 3.0s, her velocity has changed to 3.1m/s. How many seconds after she originally fell did she finally come to a stop? (Assume constant acceleration) Homework Equations Δd = 1(v1+v2)Δt...

Okay, first post... don't be too hard on me! Just got around to joining the forum even though i have been browsing for quite some time. Homework Statement A sprinter can accelerate with constant acceleration for 3.30 before reaching top speed. He can run the 100-meter dash in 10 s...

Homework Statement There are two ships separated by a distance \gamma along a straight coastline. Ship A starts moving perpendicularly to the coastline , and Ship B moves such that its velocity vector always point along the position of Ship A. Both ships move at same constant speed. After...

I've done a countless number of these problems before, so I was quite annoyed when I was unable to do this one. It's from Griffiths' Intro to Elementary Particles. Homework Statement A pion traveling at speed v decays into a muon and a neutrino, \pi^- \rightarrow \mu^- + \bar{\nu}_\mu If...

Homework Statement To find the height of an overhead power line, you throw a ball straight upward. The ball passes the line on the way up after 0.70 s, and passes it again on the way down 1.2 s after it was tossed What is the height of the power line? m What is the initial speed of...

Here's the question: An antiaircraft gun fires shells at 200 m/s at a 60° angle. An enemy plane flies directly toward the gun at 300 m/s, 495 m off the ground. How far away (horizontally) must the plane be when the gun fires for the shell to hit the plane? First off, I know I get two solutions...

Here is the problem I am trying to do: A sprinter can accelerate with constant acceleration for 3.8 s before reaching top speed. He can run the 100 meter dash in 15.0 s. What is his speed as he crosses the finish line? I'm currently trying to break this into two separate intervals. I...

Homework Statement http://img413.imageshack.us/img413/2919/physicsprobpr6.jpg Xy=2400 m Homework Equations Xy=Voyt + 1/2at^2 Xx=1/2(Vox+Vx)t The Attempt at a Solution I calculated the vertical and horizontal velocity components of the given resultant velocity of 240 m/s...

Suppose a car traveling at 12.0m/s sees a traffic light turn red. After 0.510s have elapsed, the driver applies the brakes, and the car decelerates at 6.20m/s^2. What is the stopping distance of the car, as measured from the point where the driver first notices the red light? Homework...

I'm fairly new with this so I hope I've posted at the right place! I don't understand how to go about doing the following kinematics problem: Two stones are dropped from the edge of a 60-m cliff, the second stone 1.6s after the first. How far below the top of the cliff is the second...

I'm fairly new with this so I hope I've posted at the right place! I don't understand how to go about doing the following kinematics problem: Two stones are dropped from the edge of a 60-m cliff, the second stone 1.6s after the first. How far below the top of the cliff is the second...

A motorist is traveling at 18 m/s^2 when he sees a deer 38 m ahead. If the maximum negative acceleration is -4.5 m/s^2, what is the reaction time (delta t) of the motorist that will allow him to avoid hitting the deer? Answer in units of 's'. I tried using x(t)=x0+v0t+1/2at^2 and it didn't...

Hey, all. A few days ago, I posted a poorly-worded kinematics problem, at https://www.physicsforums.com/showthread.php?p=1195234#post1195234. I received a helpful answer practically within minutes, and shortly thereafter realized the answer was irrelevant, and that the fault lay in my...

Not actually homework, but almost definitely not graduate-level stuff. No clue how to use LaTeX, so I'll have to give variables nonstandard names to make this legible. Homework Statement An object (say, a spaceship, or something. Something that can accelerate/decelerate at a constant...

A swimmer who can swim at a speed of 0.8 m/s in still water heads directly across a river 86m wide. the swimmer lands at a position on the far bank 54m downstream from the starting point. determine: a) the speed of the current b) velocity of swimmer relative to the shore c) the direction of...

Hi, I have a kinematics problem involving free fall acceleration. I'm not sure how to do this so I was wondering if someone could please give me a hand. Thank you. Question: Water drips from the nozzle of a shower onto the floor 2m below. The drops fall at regular (equal) intervals of...

Hello, I am a tenth-grader physics student, and I have a mechanics-realted problem you may think is quite trivial, but I have been unsuccessfully trying to solve it for a whole day, so I would thank you if you answered. Please consider the attached graph; the question relates to it: Two...

Sorry, I should have posted this in my other thread! Here's the information for the question: "A man is running at speed c (much less than the speed of light) to catch a bus already at a stop. At t=0, when he is a distance b from the door to the bus, the bus starts moving with the positive...

A stone is DROPPED off a 144 foot cliff. A second later, another stone is THROWN off that cliff. The two hit the water at the same exact instant. What is the initial velocity of the second stone? The answer is 40 ft/second according to my book, but for some reason, I never get that. I...

Hey guys, There is one more question I am having a problem with. Here it is: You jump from the top of a boulder to the ground 2.07 m below. Calculate your deceleration on landing. Assume that in order to soften your landing, your legs will bend 0.510 m. Give your answer in units of g. Do...

Hey guys, I just joined and I have a question. Here is my problem: Sitting in a second-story apartment, a physicist notices a ball moving straight upward just outside her window. The ball is visible 0.291 s as it moves a distance of 1.22 m from the bottom to the top of the window. What is...

A stone falls freely from rest and the total distance covered by it in the last secon of its motion equals the distance covered by it in the fist 3 seconds of its motion.How long does the stone remain in air? I got the answer as 3 secs but my book says it is 5 (much more logical too). Can...