Really easy 1-d motion question

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SUMMARY

The discussion centers on a physics problem involving a motorcycle cop accelerating with a constant acceleration, a, while a car travels at a constant velocity, Vcar. The key conclusion is that the cop must first reach the car's speed before he can begin to close the distance. The misunderstanding arises from incorrectly applying relative motion concepts, specifically assuming the cop's initial velocity is -Vcar and using the equation 0 = Vo + at without considering the need for the cop to match the car's speed before overtaking it. The correct approach involves analyzing the cop's acceleration until he reaches the car's speed and then calculating the distance and time to catch up.

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  • Understanding of kinematics, specifically equations of motion.
  • Familiarity with concepts of relative motion in physics.
  • Knowledge of constant acceleration and velocity definitions.
  • Ability to solve basic algebraic equations related to motion.
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  • Study the kinematic equations for uniformly accelerated motion.
  • Learn about relative velocity and its applications in physics problems.
  • Explore graphical representations of motion to visualize acceleration and velocity.
  • Practice solving problems involving multiple objects in motion with different velocities.
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This discussion is beneficial for physics students, educators, and anyone interested in understanding motion dynamics, particularly in scenarios involving acceleration and relative motion. It is especially relevant for those preparing for exams in mechanics or looking to strengthen their problem-solving skills in physics.

mewmew
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Ok, I have a pretty dumb question. A motorcycle cop starts to accelerate with a constant acceleration, a , at the same time a car goes by with a constant velocity, Vcar, find what time it takes to reach the car, the distence, etc. Now, I figured it out as it was a pretty easy problem but I don't understand why it won't work in relative motion as follows: The cop has an initial velocity of -Vcar and accelerates with his acceleration a until he reaches a velocity of 0. I put it into 0 = Vo + at but that doesn't give me the right answer, so I am sure my logic of relative motion is just wrong and am wondering why? Thanks for any help, I am sure I am just not thinking of something super easy.
 
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In order for the cop to catch the car he must accelerate up to the same speed of the car (v = 0) at which point he is no longer losing ground on it. After that point he continues accelerating in order to gain on the car until he reaches it. If you want to do the problem from the other car's refrence frame you'll have to look at when the cop reaches the car's x=0 from an initial velocity of Vo and acceleration of a.
 
Your mistake is that the motorcycle's speed will be the same as the car's speed when it overtakes the car.
 

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