Solve Kinematics Problem: High Speed Train & Locomotive

AI Thread Summary
The discussion revolves around a kinematics problem involving a high-speed train and a stationary locomotive. The train is traveling at 161 km/h and needs to decelerate to avoid a collision with the locomotive, which is 676 meters ahead and moving at 29 km/h. The user initially calculated the required deceleration as -1.43 m/s² but was informed that the correct value is 0.93 m/s². Participants suggest focusing on the relative speed of the train to the locomotive and applying the appropriate kinematics formulas to solve for the deceleration. The conversation emphasizes understanding the relationship between the two speeds and the distance to determine the correct answer.
Nenad
Messages
698
Reaction score
0
Hello everyone, this problem may seem simple to all of you, but I seem to be having a mental block. My physics prof assigned some review last class and I seem to be stuck on this problem.

Here goes:
When a high speed train traveling at 161km/h rounds a bend, the engineer see that there is a locomotive lying on the track directly ahead of the moving train. The locomotive is traveling at 29.0km/h in the same direction as the train, and is 676m away when the train sees it. The engineer of the high speed trian imeediatelly applyes the brakes.
(a) that must be the decelleration of the train in order not to hit the locomotive. (friction is neglected).

Ive tried setting distance traveled of the two events equal to each other, and I keep getting a decelleration of -1.43m/s^2, but the answer is 0.93m/s^2. A helpfull hint on how to approach the problem would be fantastic.
Awaiting a reply, Thanks.
 
Physics news on Phys.org
First of all, your answer your answer for a will be negative, but the answer to the question should be positive because they ask for the decelleration.

If they are traveling in the same direction, the speed of the train with respect to the locomotive is ____ (pretent the locomotive is stationary). The distance is 676 m. What kinematics formula applies to this? Now solve for a.
 
thanx man.
 
Thread 'Minimum mass of a block'
Here we know that if block B is going to move up or just be at the verge of moving up ##Mg \sin \theta ## will act downwards and maximum static friction will act downwards ## \mu Mg \cos \theta ## Now what im confused by is how will we know " how quickly" block B reaches its maximum static friction value without any numbers, the suggested solution says that when block A is at its maximum extension, then block B will start to move up but with a certain set of values couldn't block A reach...
Thread 'Calculation of Tensile Forces in Piston-Type Water-Lifting Devices at Elevated Locations'
Figure 1 Overall Structure Diagram Figure 2: Top view of the piston when it is cylindrical A circular opening is created at a height of 5 meters above the water surface. Inside this opening is a sleeve-type piston with a cross-sectional area of 1 square meter. The piston is pulled to the right at a constant speed. The pulling force is(Figure 2): F = ρshg = 1000 × 1 × 5 × 10 = 50,000 N. Figure 3: Modifying the structure to incorporate a fixed internal piston When I modify the piston...
Back
Top