Calculating Time, Distance, and Velocity in a Kinematic Problem

In summary, the problem involves a policeman on a motorcycle chasing a truck with a speed of 96.5 km/h. The policeman has a constant acceleration of 1.83 m/s and needs to overtake the truck. The question requires finding the time and distance for the policeman to overtake the truck, as well as the velocity of the motorcycle when it catches the truck. To solve this problem, the distance between the truck and the motorcycle when they are level must be determined, and then the time can be calculated using their constant velocities.
  • #1
9giddjl
35
0
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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  • #2
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?
 
  • #3
um i don't know a distance.. or maybe I cannot see it
 
  • #4
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?
 
  • #5
they're at the same distance?
 
  • #6
so we need to find the time when the distances are the same?
 
  • #7
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:
 

1. What is a hard kinematic problem?

A hard kinematic problem is a type of problem in physics that involves the analysis of motion and its causes. It often requires the use of complex mathematical equations to solve.

2. What are some examples of hard kinematic problems?

Examples of hard kinematic problems include calculating the acceleration of objects in free fall, determining the velocity of a projectile, and analyzing the motion of objects connected by pulleys and ropes.

3. How do you approach solving a hard kinematic problem?

To solve a hard kinematic problem, you should first identify the known variables and equations that can be used to solve for the unknown variable. Then, you can plug in the values and solve the equation using algebra or calculus.

4. What are some common challenges when solving hard kinematic problems?

Some common challenges when solving hard kinematic problems include dealing with multiple variables and equations, using the correct units for calculations, and accounting for external factors like air resistance and friction.

5. How can understanding hard kinematic problems be useful in real life?

Understanding hard kinematic problems can be useful in many real-life situations, such as designing and analyzing the motion of machines and vehicles, predicting the trajectory of sports balls, and understanding the movement of celestial bodies in space.

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