Deceleration Definition and 226 Threads

Homework Statement At some critical deceleration, a seat belt will lock into place, preventing a driver/passenger from pulling it out any further. What is that critical deceleration and why? Homework Equations I have not quite figured this out yet, because it would depend on how you...

(1) 1. Homework Statement Determine the stopping distance for a car with an initial speed of 95km/h and human reaction time of 1.0s, for an acceleration (a) a = -4.0m/s^2 Initial velocity (V1) = 95 km/h = 26.38 m/s Final velocity (V2) = 0 m/s Initial Displacement (Y1) = ? Final Displacement...

Homework Statement The coefficent of static friction between the floor of a truck and a box resting on it is 0.38. The truck is traveling at 69.7 km/hr. What is the least distance in which the truck can stop and ensure that the box does not slide? Homework Equations The Attempt at...

Homework Statement You are driving to the grocery store at 18 m/s. You are 130 m from an intersection when the traffic light turns red. Assume that your reaction time is 0.50 s and that your car brakes with constant acceleration. What acceleration (magnitude) will bring you to rest right at...

Homework Statement The driver of a pickup truck going 100 km/h applies the brakes, giving the truck a uniform deceleration of 6.50 m/s^2 while it travels 20.0 m. a) what is the speed of the truck in kilometers per hour at the end of this distance? b) How much time has elapsed...

1. You are driving toward a traffic signal when it turns yellow. Your speed is the legal speed limit of v0=55 km/h.: your best deceleration rate has the magnitude a = 5.18 m/s^2. Your best reaction time to begin braking is T = .75S. To avoid having the front of your car enter the intersection...

A car has a maximum constant acceleration of 10 ft/s^2 and a maximum constant deceleration of 15 ft/s^2. determine the minimum amount of time it would take to drive one mile assuming the car starts and ends at rest and never exceeds the speed limit 55 mi/hr. Why do you need to know the...

I reeeeeeeeally need help with thiss. thanks :) Homework Statement A track runner finishes a race and begins to slow down in a uniform manner. In 3.50 seconds, she comes to a complete stop, covering 12.0 meters while doing so. What was her speed when she finished the race? Homework...

Homework Statement A 1000 kg boat is traveling at 90 km/h when its engine is shut off. The magnitude of the frictional force fk between the boat and the water is proportional to the speed v of the boat: fk = 70v, where v is in meters per second and fk is in Newtons. Find the time required...

Homework Statement NOTE: First time user. I am a member of an Ad Hoc fireball analysis group and my physics colleague is on travel. We have investigators in the field and therefore need to expedite an estimate. My background is geology and chemistry and I get "brain freeze" reasoning through...

Long story short... I am having a hard time creating natural deceleration for a VB.NET touchscreen project. I would like to be able to scroll an object and allow it to coast to a stop. The starting velocity will be set by the swipe speed of the finger. Let's call it pixels/millisecond...

[b]1. I need to find the deceleration of a bicycle, I have Finial velocity at 0, initial velocity at 5.56m/s and discplacement at 1.80m [b]2. V^2+U^2/(2*S)=A not sure if formula is correct The Attempt at a Solution I find that 0^2+5.56^2/(2*180) = -27m/s/s Is this correct? i...

First off I don't believe this would be classed as a homework question, as this is an engineering design project problem and I haven't been to school for over ten years, however if I am wrong I apologise. My problem is:- The object I want to knock down is a skittle: h = distance from...

I've nothing more than one high school class and a curiosity in physics, and I'm sure this is a simple, albient random question. Its something I was discussing with some friends the other day, and I'd like some legitimate input, instead of our uninformed guessing. Thanks to all who read and...

http://img15.imageshack.us/img15/858/masteringf.jpg a: 550-150 = 400rev change 400/60 = 6&2/3 rev/s (converted to revs) 6.66666 / 3.5 seconds = 1.9 rads^-2 since it's decelerating i put -1.9 rads^-2 now part two i got wrong, b: \thetaf=\thetai + \omegai * t +...

Is there a way to calculate the acceleration (in g's) applied to a truck as it is stopped in a runaway escape ramp? Do I need to know how long it takes or how far it goes in the ramp to calculate the acceleration?

Homework Statement Basically i need to find the braking distance and time for the deceleration of a vehicle for the following conditions, using a parachute using a parachute, and wheel brakes does anyone know of a suitable formula to calculate this? Homework Equations...

We are doing a project to find the quickest time round a given track in a car. friction: k=1.6 mass of car m=750kg power of engine w=350kw g=9.8 distance x=500m After a corner, the car comes out at velocity=31.9m/s There is a 500m straight next but have to finish it at 31.9m/s for next...

I have a rocket with a top velocity of 14.16 m/s when the engine stops. How do i calculate its deceleration based on air resistance and gravity if it is flying at approximatly 45 degress?

Homework Statement You're driving down the highway late one night at 16 m/s when a deer steps onto the road 39 m in front of you. Your reaction time before stepping on the brakes is 0.50 s, and the maximum deceleration of your car is 12 m/s^2 . How much distance is between you and the...

A truck weighing 70,000 lbs. is moving at 5 fps. on level ground. The brakes are applied and decelerates over the course of 1 foot. How much lateral force will be be exerting for that 1 second. Need a formula. Thanks Signman

Homework Statement A speed trap is set up with two pressure activated strips placed across a highway, 128 meters apart. A car is speeding along at 28.8 meters per second, while the speed limit is only 19.6 meters per second. At the instant the car activates the first strip, the driver begins...

Sorry about this, must seem a trivial question, but anyways here goes. A car is traveling at 13ms^1. It is allowed to slow down natrually without appyling the brakes. The distance traveled in coming to rest is 640m. Show that the average deceleration of the car is about 0.1ms^2...

I'm trying to figure out the average deceleration of an aircraft that touches the ground at 104 knots (175.53 ft/sec) and decelerates to zero in 3200 feet? Does anyone know how to do this? Thank you very much to all who reply.

This is the first time I have encountered a problem like this, and have no idea how to set it up, let alone solve it. Any help would be great. Homework Statement A car can decelerate at -5.00 m/s2 without skidding when coming to rest on a level road. What would be the magnitude of its...

Homework Statement A 4200lb vehicle is cruising down the highway at 65mph when the driver steps on the brake applying a braking force of 2,850lbs Determine the time to stop, assuming uniform deceleration Distance traveled during the deceleration Velocity of the vehicle after 3.2 sec's of...

Hey, Just wanted to clarify that this was the right way to calculate the deceleration when braking from a speed of 100km/h when the braking distance of the car is 45.73m. I am just using the formula v^2 = u^2 + 2as Which i have rearranged to find a... a = (v^2 - u^2)/2s...

I apologize for my ignorance, I'm an extreme newbie in physics. Is it possible to determine the deceleration rate of a car only with following information? initial velocity = 60mph (96km/h) final velocity = 0mph (0km/h) distance = 146ft (44.5m) if so, how many distance would it take to...

Im trying to figure out the maximum deceleration possible for a car coming into a corner at two points... I found the answer to the max. deceleration for the car right before the corner, but I can't get the correct answer for when the car is actually in the corner... im looking for the...

Hello... If an object weighs 4500kg and travels @ 5kph (138cm/s) then stops in 15cm: what is Gforce? Decceleration? Also, if object was stopped via a collision and if contact face is 100cmx15cm then what is impact force kg/sq.cm? This information is really important to me for a...

My first post here. My level of expertise in this field = 0, although my interest is very high! If I understand well what I've been reading: after the BB the universe starting expanding then the expansion slowed down then for the last 5 billion years the expansion reversed its course...

I'd like to see an example of a formula describing the position of a rolling ball over time. It has been given one impuls at the start, after which air resistance and friction decelerates it (the ground is flat). At high speed the ball might be sliding, until it decelerates to some treshold...

[SOLVED] Kinematics: Average Deceleration Underwater Hello! First poster here. :cool: Here is a tough question from my online HW: Homework Statement A person jumps off a diving board 5.0 m above the water's surface into a deep pool. The person’s downward motion stops 1.6 m below the...

Homework Statement "At the base of a hill (blah blah) there is a ramp inclined with an angle of 30 degrees and has a surface with a coefficient of friction of 1.5. How long should this ramp be to be able to stop a 80,000lb truck traveling at 80 mph" Homework Equations (delta)K + (delta)U...

I do not understand vehicle deceleration. The Attempt at a Solution d = µg 6.687 = .7 * 9.81 d = 6.687 m/s My question is...is it always figured out this way when dealing with vehicles.

If I accelerate to .9c I am gaining mass, but if I reverse thrust and decelerate why aren't I still adding mass since I'm still putting energy into the system? I thought it wasn't about speed but about changing speed. It takes energy to slow down as well. Or does deceleration lower mass? Or does...

You are driving your car and the traffic light ahead turns red. You apply the brakes for 3.59 s, and the velocity of the car decreases to +4.99 m/s. If the car's deceleration has a magnitude of 2.53 m/s2, what is the car's displacement during this time? I know Δd=Vi(Δt)+1/2at2. I am not...

Homework Statement A lamp hangs vertically from a cord in a descending elevator that decelerates at 1.4 m/s2. (a) If the tension in the cord is 56 N, what is the lamp's mass? (b) What is the cord's tension when the elevator ascends with an upward acceleration of 1.4 m/s2? Homework...

The problem says: A box is given a push so that it slides across the floor. How far will it go, given that the coefficient of kinetic friction is 0.20 and the push imparts an initial speed of 4.0 m/s. I can't find the applied forced because i don't know the time or distance it took to get...

Homework Statement A 27 lb meteorite struck a car, leaving a 27 cm deep in the trunk. If the meteorite stuck the car with a 520 m/s what was the magnitude of deceleration assuming it to be constant Homework Equations None The Attempt at a Solution I have to be honest I have no clue...

Homework Statement The driver of a pick up truck going 100 km/h applies the brakes, giving the truck a uniform deceleration of 6.5m/s(squared) while it travels 20.0 m a) what is the speed of the truck in km/h at the end of tihs distance b) how much time has elapsed her is the thing i...

Quick "Equations of Motion" questions (2). Rxn time; deceleration 1. A meteorite strikes on October 9, 1992, a 27-pound meteorite struck a car in Peekskill, NY, leaving a dent 22 cm deep in the trunk. If the meteorite struck the car with a speed of 130 m/s, what was the magnitude of its...

hi. I'm fairly new at physics but i got put in AP Physics and i think i could make it with some help. Could anybody please explain how to solve this problem? A speed trap is set with 2 pressureactivated strips placed across a highway, 110 m apart. A car is speeding along at 33 m/s, while the...

I posted a question as thus : A train moving at 100 km/hr uniformly decelerates at a rate of 10 km/hr each hr. How far does it travel before stopping ? A few people interpreted the wording of the question to mean the train travels through each hr at a constant speed and then on the cusp...

Homework Statement Swati was driving her car over the speed limit when an oncoming car car flashes its lights warning her of a radar trap ahead. She decelerates from 39 m/s to 27 m/s in 6.0 s. What deceleration did her brakes apply? - I am not sure what formula to use so does anyone have a...

Homework Statement A circular saw blade completes 1200 revolutions in 40s while coasting to a stop after being turned off. Assuming constant deceleration, what are the angular deceleration, and the initial angular speed?? Homework Equations v=wr w^2=w0^2 + 2alpha*delta(theta)...

Homework Statement A car traveling at 22.0 m/s runs out of gas while traveling up a 25.0 degree slope. How far up the hill will it coast before starting to roll back down?Homework Equations Vf^2 = V0^2 + 2ax x = V0t + (1/2)at^2 (maybe?)The Attempt at a Solution I am using an online homework...

as my high school physics teacher stressed, deceleration does not exist. it was a forbidden word in my introductory physics class. I do indeed partly agree with my teacher. Since if deceleration is a vector quantity, it would be very confusing since deceleration sort of implies the "negative"...

I have a rectangular block (propellar) with known width, thickness, legth, and uniform density. It is spinning at a constant angular velocity around its centroid. Then it is decelerated at a constant rate to rest. I want to find the relation between the radial distance from the centroid and...

The driver of an automobile traveling at 80 km/h suddenly slams on the brakes and stops in 2.8 s. What is the average deceleration during braking Velocity of driver=(80 km/h)(1 h/3600 s)(1000 m/1 km)=22.22 m/s average acceleration=change of velocity/time elapsed Acceleration = final...