Calculating Time, Distance, and Velocity in a Kinematic Problem

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    Hard Kinematic
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Homework Help Overview

The problem involves a kinematic scenario where a policeman on a motorcycle accelerates to catch up with a speeding truck. The truck's speed is given, and the policeman's acceleration is specified. The discussion revolves around calculating the time, distance, and final velocity of the motorcycle when it overtakes the truck.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the initial conditions, including the policeman's initial velocity and whether his final velocity equals that of the truck. There are questions about the distance between the motorcycle and the truck at the moment of overtaking and how to determine when their distances are equal.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. Some guidance has been provided regarding the relationship between the distances of the motorcycle and the truck, but there is no explicit consensus on the approach to take.

Contextual Notes

Participants note the lack of specific distance information and express uncertainty about the initial conditions and assumptions related to the problem setup.

9giddjl
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hard kinematic problem, need...help...pls:)

Homework Statement


A policeman (on a motorcycle, with the engine going) is hiding behind a bush on the side of the road when a speeding truck passes with a speed of 96.5 km/h. As the truck passess he sets off with an acceleration of 1.83 m/s, which he maintains until he overtakes it. Calculate:
a) the time he took to overtake the truck
b) the distance he traveled in doing so
c) the velocity, in km/h, of the motor cycle when it catches the truck.


Homework Equations




The Attempt at a Solution



Well first i converted 96.5 hm/h into m/s which is 26.8 m/s and i know that his acceleration doesn't change, I am just wondering is the policeman's final velocity the speed that the truck is traveling at which is 26.8 m/s? And is his initial velocity 0? and his acceleration is 1.83 so i thort that i cud use v=u+at to work out a)
i think I am on the wrong track though actually I pretty sure I am. Can someone pls help me and also can sum1 pls tell me sum things that i shud look out for when trying to solve these really hard straight line motion questions. Like i get the simple ones but it is just ones similar to these that i find difficult. I appreciate all the help! Thankyou!:)
 
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9giddjl said:
im just wondering is the policeman's final velocity the speed that the truck is traveling at which is 26.8 m/s?
You can't assume that the final two velocities are the same, in some cases it may very well be that the two have the same final velocity, but this is not generally the case.

Instead, what do you know about the distance between the truck and the bike at the time your trying to find?
 
um i don't know a distance.. or maybe I cannot see it
 
9giddjl said:
um i don't know a distance.. or maybe I cannot see it
When the bike is level with the truck, where is their separation?
 
they're at the same distance?
 
so we need to find the time when the distances are the same?
 
9giddjl said:
they're at the same distance?
9giddjl said:
so we need to find the time when the distances are the same?
Correct :approve:
 

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