Kinematics chasing problem: Car vs. Motorcycle acceleration question

In summary, the student catches up to Mr. Horn after a head start of 1.75 m and has a speed of 4.90 m/s2.
  • #1
jerad908
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Homework Statement
Another physics student ‘borrows’ a sports car for a joy ride and discovers that it can accelerate at a rate of 4.90 m/s2. He decides to test the car by challenging Mr. Horn and his motorcycle. Both start from rest, but the student is so confident in his new ride that he gives Mr. Horn a 1.00 s head start. If Mr. Horn moves with a constant acceleration of 3.50 m/s2 and the student maintains his acceleration of 4.90 m/s2, find:
(a) the time it takes the student to overcome Mr. Horn.
(b) the distance he travels before he catches up with Mr. Horn.
(c) the speed of both vehicles at the instant the student overtakes Mr. Horn.
Relevant Equations
Big 5 equations
Im for some reason getting 1.58 s for time.

I found 1.75 m as the head start distance and then I do d=d so: 2.45t^2 = 1.75t^2 +1.75

but the answer for "a" should be 6.45s...
 
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  • #2
Why don't you show your work on this one. Given the ambiguity in the previous, perhaps start by saying if you chose ##t_0## after the "headstart" for part a). Does your answer line up with that of the book if you change that ?
 
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  • #3
jerad908 said:
Homework Statement:: Another physics student ‘borrows’ a sports car for a joy ride and discovers that it can accelerate at a rate of 4.90 m/s2. He decides to test the car by challenging Mr. Horn and his motorcycle. Both start from rest, but the student is so confident in his new ride that he gives Mr. Horn a 1.00 s head start. If Mr. Horn moves with a constant acceleration of 3.50 m/s2 and the student maintains his acceleration of 4.90 m/s2, find:
(a) the time it takes the student to overcome Mr. Horn.
(b) the distance he travels before he catches up with Mr. Horn.
(c) the speed of both vehicles at the instant the student overtakes Mr. Horn.
Relevant Equations:: Big 5 equations

I'm for some reason getting 1.58 s for time.

I found 1.75 m as the head start distance and then I do d=d so: 2.45t^2 = 1.75t^2 +1.75

but the answer for "a" should be 6.45s...
I found 1.75 m as the head start distance and then I do d=d so: 2.45t^2 = 1.75t^2 +1.75
Not only does Mr. Horn have a head start distance. He also has a head start velocity which you did not take into account.
 
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  • #4
Instead of trying to figure out the head distance and velocity, it's easier to choose the appropriate "Big" equation and write the position of each vehicle at any time ##t## as shown by the same clock which starts when the first vehicle starts moving. Then say that there is a specific time ##t_c~##, the catch-up time, at which the two vehicles are at the same position. No reason to figure out anything else - just solve for the catch-up time.
 
  • #5
Can someone show maths to solve this questions? Thx
 
  • #6
DannoXYZ said:
Can someone show maths to solve this questions? Thx
No, you've been here long enough to know that we don't give solutions when asked. This thread is old enough that it might be okay to show the solution, but what if you have a new homework assignment that matches it?

Instead, please start a new thread in the HH forums with the problem statement and show your work on the solution. If you're having trouble with the equations, we are happy to help once you show your efforts. Thanks.
 
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FAQ: Kinematics chasing problem: Car vs. Motorcycle acceleration question

What is the Kinematics chasing problem?

The Kinematics chasing problem is a physics problem that involves two objects moving at different speeds in the same direction, with one object trying to catch up to the other. It is often used to illustrate concepts of relative motion and acceleration.

How is the Kinematics chasing problem solved?

The Kinematics chasing problem can be solved using equations of motion, specifically the equations for position, velocity, and acceleration. By setting the equations for both objects equal to each other and solving for time, you can determine when the two objects will meet.

What is the difference between car and motorcycle acceleration in the Kinematics chasing problem?

The main difference between car and motorcycle acceleration in the Kinematics chasing problem is the acceleration rate. Motorcycles typically have a higher acceleration rate than cars, meaning they can cover more distance in a shorter amount of time. This can affect the outcome of the problem and the time it takes for the motorcycle to catch up to the car.

How does the initial distance between the car and motorcycle affect the Kinematics chasing problem?

The initial distance between the car and motorcycle does not affect the final outcome of the Kinematics chasing problem. As long as the two objects are moving in the same direction, the time it takes for the motorcycle to catch up to the car will remain the same, regardless of the initial distance between them.

What other factors can affect the Kinematics chasing problem?

Other factors that can affect the Kinematics chasing problem include the initial velocity of both objects, the acceleration rate of both objects, and any external forces acting on the objects, such as friction or air resistance. These factors may alter the outcome of the problem and should be taken into consideration when solving it.

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