Deceleration Definition and 229 Threads

Homework Statement When you slam on the brakes your car decelerates but this is not constant as it starts at a higher value and then reduces. This has something to do with the coefficient of friction between the brakes and the discs, but what is it and what are the reasons for this...

Homework Statement Using Friedmann equations find the parameter of deceleration q_0 using relative densities \Omega_M,\ \Omega_R,\ \Omega_\Lambda. Homework Equations Friedmann equations, deceleration parameter: q_0=-\frac{\ddot{a_0}a_0}{\dot{a_0}^2} The Attempt at a Solution So from...

Suppose there are two planets A and B, each stationary relative to the other at distance x. Now an observer travels from planet A to B. He sees that the distance between them has shortened. If the clocks on the two planets are synchronised, then with the help of a Minkowski diagram, it could be...

Homework Statement if we have an f1 car decelerating from 320km/hr to 68km/hr in 130 meter. what would be the equation needed to calculate the time taken by the car to decelerate those 252km/hr Homework Equations The Attempt at a Solution

What is the difference between decreasing acceleration, deceleration and negative acceleration? Most importantly, i want to clarify that acceleration is the rate of change of velocity over time, it Does not necessarily mean that the car velocity is increasing and that a car is speeding up when...

I'm not entirely sure of my answer, if it's wrong could some one point me in the right direction? Homework Statement A 140g ball is falling through the air at 36 meters per second (constant speed) prior to time 0. The ball impacts the floor at time 0. The ball decelerates until time 0.012...

Hey friends. I wanted to know how exactly would a dynamicist define deceleration of a car on a road with humps and dips. Actually I always thought that deceleration of car on the road will be the vector a (see the diagram), however, in a sample problem in my dynamics book, it the car's...

Hey everyone Homework Statement Im trying to calculate the force encountered by an object falling due to gravity that is caught by a rope. Obviously F=ma and since mass is constant I need to find the rate of deceleration. I've tried to using the equation v^2 = u^2 +2ax as v = 0 and u...

a motorcycle starts from rest point A and travels 300m along a straight horizontal track to point B where it comes to a stop. if the acceleration is limited to 0.7g and deceleration to 0.6g calculate the least possible time to cover the distance and maximum velocity reached. Can anyone point...

I understand we don't know if the universe is finite or infinite, but I know that in the center of the Earth there is no gravity because the attraction from Earth's gravity is the same on all directions, so the final result is zero. So, if the universe is infinite and matter is equally...

Homework Statement The braking distance is the distance the car travels while decelerating once the brakes have been applied. A car of mass 450kg is traveling at a speed of 70MPH (31.3ms-1) when the driver makes an emergency stop. Calculate the deceleration of the car (Assume a uniform...

in acceleration time graph when the acceleration is constant. Then at an instant it has negative acceleration. Does this mean that the body is decelerating or it is accelerating in the opposite direction. eg. http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/motgraph.html {last graph}

Hello, Running a FEA on a object and need to calculate the deceleration from 5mph to 0mph and 10mph to 0mph . The vehicle weight is 2935lbs. They ran one test and said the vehicle stopped after it crumpled just less than 1". (I assume we can use the distance and velocities to solve the time...

Homework Statement A cat drops from a shelf 3.7ft above the floor and lands on all four feet. His legs bring him to a stop in a distance of 12cm. Part A: Calculate his speed when he first touches the floor (ignore air resistance). Part B: Calculate how long it takes him to stop. Part C...

Hello people In this thread I am interested in how to calculate Newtons or force from a falling object being stopped by someone or something such as a machine. In my example below is a scenario- A 6000 ton ball of iron moves from directly above this person who is roughply 2 meters tall...

You are driving down the highway late one night at 20 \rm m/s when a deer steps onto the road 35 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 10 m/s^2 . How much distance is between you and the deer when you come to a...

So I got a ticket a few days ago for running a red light, the yellow light was very short, I'm trying to figure out if the city set the yellow light too short to be reasonable. The speed limit at that location is 50 mph, the yellow light is 4 seconds. Federal motor vehical safety standards...

Homework Statement An engineer in a locomotive sees a car stuck on the track at a railroad crossing in front of the train. When the engineer first sees the car, the locomotive is 250 m from the crossing and its speed is 12 m/s. If the engineer’s reaction time is 0.36 s, what should be...

Not a homework question for me but one i was asked and would like to know how? A truck traveling at 100km/h (27.7m/s) goes up a ramp inclined at 30', If it takes the truck 10 seconds to stop how far does the truck travel (m)? Working out for a straight line is easy however i am unsure of...

Homework Statement A coin is rolled without slipping on a table top in a straight line. It starts rolling at 3.4 rad/s and slows down at a constant angular acceleration. It is rolling at 1.2 rad/s when it falls off the table edge. If the radius of the coin is 0.011m, and the edge of the...

Homework Statement A cyclist traveling at 8.8725 mps, brakes coming to a halt in 100m, what is the average angular deceleration of the rear wheel. The diameter of the wheel is 650mm The Attempt at a Solution (v² - u²)/2s = a (0-8.8725²)/2x100 = -0.393 mps

Could anyone please tell me which is right and why. A person lifts 80pounds or 80% of his RM {one repetition maximum lift} for the last 40% of the concentric lift, the weight decelerates. Which or can both of these be deceleration and why please. 1, His RM = 100 pounds, so for the...

Homework Statement I did an experiment in which we gathered velocity-time data for a cart slowing down and speeding up on a ramp. The two acceleration values I calculated from the data were 0.4768m/s^2 and 0.4203m/s^2. Why are the values different (remember that there isn't any applied force...

Homework Statement ok i just need an explanation for one tiny thing. a drop-forge hammer of mass 1500kg falls under gravity on to a piece of hot metal which rests in a fixed die. from the instant the hammer strikes the piece of metal until it comes to rest, the hammer is decelerating at 1.5...

Homework Statement True or False Homework Equations Deceleration is always in the negative direction. The Attempt at a Solution true.

I have just started a calculus book, and I can't figure out how to solve this problem: Homework Statement The landing velocity of an airplane (i.e., the velocity at which it touches the ground) is 100 mi/hr. It decelerates at a constant rate and comes to a stop after traveling 1/4 mile...

i'm curious, if there are one or not.

Homework Statement Contact lenses being manufactured in space are returned in a re-entry capsule to Earth for distribution and sale. If the re-entry velocity is 7.4km/s and the re-entry flight-path angle is 10 degrees, determine the maximum deceleration it will experience and at what...

Homework Statement To stop a car, you require first a certain reaction time to begin braking; then the car slows down under the constant braking deceleration. Suppose that the total distance moved by your car during these two phases is 186 ft when its initial speed is 50 mi/hr, and 80 ft when...

Homework Statement Block B has an initial velocity of 2.0 m/s to the right and is sliding across the surface of block A. Block A is resting on ideal, frictionless ice. Given the following, information: a) The rate of "deceleration" of block B b) The rate of acceleration of block A c)...

I need help please! Angular deceleration Homework Statement A circular saw blade completes 1150 revolutions in 42 s while coasting to a stop after being turned off. Assume constant deceleration. (a) What is the angular deceleration? (rpm/s) (b) What is the initial angular speed? (rpm)...

Homework Statement A bicycle is turned upside down while its owner repairs a flat tire. A friend spins the other wheel of radius 0.4 m and observes that drops of water fly off tangentially. She measures the height reached by drops moving vertically. A drop that breaks loose from the tire on...

Quick PLEASE help :( Homework Statement A car can decelerate at -4.80 m/s2 without skidding when coming to rest on a level road. What would its deceleration be if the road were inclined at 13\circ uphill? Assume the same static friction coefficient.Homework Equations Ff=\muSFNThe Attempt at a...

Homework Statement A man on a bicycle, of total mass 100 kg, is free-wheeling at a constant speed of 15ms^-1 down a hill with a gradient 10% (i.e. sin^-1(0.10)). He wants to slow down to a safer speed, so he applies the brake lightly to produce a constant braking force of 84 N. The air...

Calculating deceleration...need quick help, please Homework Statement Traumatic brain injury such as concussion results when the head undergoes a very large acceleration. Generally, an acceleration less than 800 m/s2 lasting for any length of time will not cause injury, whereas an...

Homework Statement A 2500 kg truck collides into a 1250 kg car. Both cars were traveling the same speed in opposite directions. Which car has the greater deceleration rate? 2500 kg truck 1250 kg car the same deceleration Homework Equations J=Pf-Pi=Ft The Attempt at a Solution...

Hi all, Embarassed to ask as seems simple, i have done the maths but answer seems too low! - have looked all over for worked example to follow but no luck :( I have a free rolling mass of 2200kg that is being driven down a slope at 0.204m/s. This mass must be braked to a stop in 0.5m i...

Ok, so I was doing this problem, *NOT* a homework problem, where I was solving for the force (and eventually, the work) required to move a body with a mass of m distance x in a given time y. I know that theoretically there would not be any force because there is no given acceleration and...

If a top fuel dragster that can accelerate to 325mph in 5sec. in the quarter mile suddenly had its drive train precisely and instantaneously severed when the car reached 300mph would the momentum or the inertia of the rapid acceleration cause the car to exceed 300mph? If other words, would the...

I think I solved this whole thing but it seems a bit too simple. I think I might've missed a detail somewhere. This is the problem, followed by my steps: Homework Statement Two cars are about hit each other (face to face). The first car is doing 20m/s and decelerating at a rate of 5m/s^2...

Alright, once again I've failed myself and now I think I've wasted way too much time on trying to figure this out. I just want a bit of help in setting this thing up and perhaps a short description of which variables I need to find first. Any help, much appreciated of course. Thanks all...

If deceleration is given instead of acceleration can i find the force ?

An object decelerates from 20 m s to 10 m s. Deceleration is a constant 2.50 m s−2. Firstly, time taken. change in speed over deceleration? Would make it 4 seconds. Is that correct? Secondly how do I calculate the distance covered? Is it simply change in speed x time which would make it...

Homework Statement A lorry is driving at 96 km h^−1. The driver decelerates to a speed of 48 km h^−1. Given that the deceleration is 2.68 m s^−2 find the distance over which the brakes are applied. I know the initial speed of the lorry, v = 96 km h^-1 = 26.67 m s^-1 I know the final...

Greetings, First post here. I am trying to calculate the force applied to a 150 lb. person riding in a vehicle that decelerates from 12mph to 8 mph in .5 seconds. If I am understanding correctly the formula is: Initial velocity-Final Velocity/.5 So 12-8/.5 = 8 The to calculate...

Homework Statement When an F-18 jet lands on the runway, it's position is defined by s(t)=189t-t^7/3 meters after t seconds calculate the braking time calculate the deceleration when the jet stops ( i think she means immediately before?) Homework Equations derivative The...

Homework Statement A friend of mine gave me this problem to solve and I have no idea where to begin: A car weighing 5000lbs traveling at 160km/hr with a payload of 45 kg on the roof hits a wall and stops after crumpling 3 ft. What is the minimum strength of the bond to hold the payload on...

Did the universe changeover from deceleration to acceleration exactly after the moment when the increasing repulsive force became equal to the decreasing gravitational force? [Would like to confirm if that would be consistent with the fact that acceleration starts when the mass density of the...

The maximum deceleration of a car... Homework Statement The maximum deceleration of a car on a dry road is about 8.0 m/s^2 The Attempt at a Solution A) If two cars are moving head-on toward each other at 88 km/h (55 mi/h), and their drivers apply their brakes when they are 85 m apart...

Homework Statement Leroy, who has a mass of 100kg, is skateboarding at 9.0 m/s when he smacks into a brick wall and comes to a dead stop in .2s a. Show that his deceleration is 45 m/s^2. b. Show that the force of impact is 4500N. Homework Equations I think the only equations that...