Deceleration Definition and 229 Threads

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...

I'd appreciate some help with this physics problem: A car is traveling 10 km/hr and crashes into a tree. The driver is thrown 1 m forward. What is his average deceleration? Here's my work: Velocity of driver: 10 km/hr = 10,000 m/hr = 250/9 m/s Time: 1 m / 250/9 m/s = .036 s So it...

I got a problem with my notes in introduction to mechanics. In the 1st picture, why the deceleration should be " a=-g-kv" instead of " a=-g+kv" ? The air drag should be against the motion. the motion is downward, then the drag should be pointing upward. So I think it should be "positive"...

Deceleration (Driving a Car--Help) You're driving down the highway late one night at 20m/s when a deer steps onto the road 35m in front of you. Your reaction time before stepping on the brakes is .5s, and the maximum deceleration of your car is 10m/s. A. How much distance is between you...

Ive been trying to fiure out how to get this answer but am just have some serious trouble. A 27 pound meteorite struck a car, leaving a dent 27 cm deep in the trunk. If the meteorite struck the car with a speed of 520 m/s, what was the magnitude of its deceleration, assuming it to be...

Hi Another question It says: A car is traveling at 72km/hr. At a certain instant its brakes are applied to produce a nonconstant deceleration of s"(t)=-t(in m/s^2) How far does the car travel before coming to rest? Now there's a lot of questions like this in the book, however they use a...

This is not homework. I'm an old game programmer :smile: There is a platform moving at a constant velocity 100. The distance to the 'end' is 75. I have 50 clock ticks to begin slowing down at a constant rate so the platform reaches the end spot and is at zero velocity at the end of the...

With motion problems, what formula do i use for deceleration of a particle if I am given v and a, and need to find distance?

cars A and B are d=60m apart and traveling at u(A)=8.89 and u(B)=6.67.knowing that 45s after driver A apply his brake to avoid overtaking B,the two cars collide,determine the uniform deceleration of car A. i have tried to form eqns using s=ut + 1/2a(t^2) for both cars and substitute into [car...

I have heard of a lifting reentry that is used for lessening the deceleration on reentry. Can anyone explain how this works?:confused:

Hey! I have this question that I can't find the answer to anywhere! The Brakes of an automobile can decelerate at 6.00 m/s2. a) How many seconds are required to stop the automobile if it is traveling at a rate of 27.0 m/s? b) How many meters does the automobile travel during this...

Hi, I need help with the following problem... The speed limit of a school zone is 40km/h. A Driver driving at this speed sees a child that crosses the street 13m in front of the car. He applies the brakes and desacelerates at 8m/s^2. If the reaction time of the driver is 0.50s, will the car...

i don't know why I'm having so many problems but I greatly appreciate the help! 1) A train normally travels at a uniform speed of 72 km/hr on a long stretch of straight, level track. On a particular day, the train must make a 2.0-min stop at a station along this track. If the train decelerates...

the source of all electromagnetic radiation is the acceleration or deceleration of charged particles, mostly electrons….only when an electron jumps down energy levels, a photon/ electromagnetic wave is emitted…sounds contradicting to me, how can be both correct? Hope question isn’t too silly.

I have a roulette wheel and a ball spinning in opposite directions First I need to know how to calculate the deceleration of the wheel if I want it to stop over a distance of 370 degrees. I have d, Vi, and Vf=0. I have this formula which seems to work but does not look right...

Ok here is my question. Take a person riding a bike. If you can calculate their momentum by knowing their total weight and speed, how could you calculate the DISTANCE they will roll if they stop pedalling and apply no force. Assume that there is absolutely no wind at the time. And add in a grade...

Can anyone tell me the drag of a standard bullet? I realize there are lots of variables affecting this, but what is the ideal amount of drag without considering particulr weather conditions.

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 teh car, the locomotive is 210 m from the crossing and its speed is 10 m/s. If the engineer's reaction time is .22 s, what should be the magnitude of the minmum...

A speed trap is set up with two pressure-activated strips placed across a highway, 116 m apart. A car is speeding along at 31.5 m/s, while the speed limit is 21 m/s. At the instant the car activates the first strip, the driver begins slowing down. What minimum deceleration is needed in order...

This, to most of you, is probably easy to work out. I have the following question: A car has a mass of 900kg and is traveling at 35m/s on a motorway. The driver sees that a queue has developed and applied the brakes to give the car a decelerating force of 2000N until it comes to rest. What...

A 0.5m cube is sitting on top, and at the end, of a 1m wide by 3m long board. Both the cube and board are traveling at a constant velocity of 10 m/s. The board begins to decelerate at -8.5 m/s squared. The cube decelerates across the top of the board at -3 m/s squared. How much time will it take...

The question reads: A commuter train travels between two downtown stations. Because the stations are only 1.00km apart, the train never reaches its maxium possible cruising speed. The engineer minimizes the time t between the two stations by accelerationg at a rate a1=0.100m/s^2 for a time t1...

I have a smal brain but am trying to help an elderly gentleman (who doesn't speak too good English) with his theories. He talks about a "twon" or tuon in relation to the rapid deceleration of photons, producing eletron-positron pairs. I can't find any particle or process similar to this...

1. A cab driver picks up a customer and delivers her 2.00km away, on a straight route. The driver accelerates to the speed limit and, on reaching it, begins to decelerate at once. The magnitude of the decelerates is three times the magnitude of the acceleration. Find the lengths of the...

I have a question that I have been working on, but I am stuck and not quite sure if i am approaching the problem right. The question asks: a person is driving 30.0 m/s 23 degrees north of east when a person walks out in front of them. The person slams their brakes and turns the cars wheels...

Hey all, I have a question. How can I calculate the deceleration of an object that begins to go up an incline of angle X? See there are a lot of problems like this. One of mine for example involves an object entering an incline of 25 degrees at 0.25 m/s, and I need to calculate how far it...

A car traveling at 45 miles per hour is brought to a stop, at constant deceleration, 132 feet from where the brakes are applied. a. How far has the car moved when its speed has been reduced to 30 miles per hour? b. How far has the car moved when its speed has been reduced to 15 miles per...