Easy one here yet, i can't get it

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A 1200kg space probe traveling at 9500 m/s fires its engines, producing a force of 92000N over 86 km, prompting a discussion on calculating its final speed. The initial approach involved finding acceleration by dividing force by mass and using the kinematic equation, but confusion arose when the initial and final velocities appeared the same. It was clarified that a constant acceleration means the final velocity should differ from the initial, emphasizing the need to convert kilometers to meters. The participant recognized a calculation error related to unit conversion, leading to a correct understanding of the problem. The discussion then shifted to a new question about a spring's force and friction affecting an eraser's distance, with participants suggesting relevant formulas.
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A 1200kg space probe traveling initially at a speed of 9500 m/s through deep space fires its engines that produce a force of magnitude 92000N over 86 km distance. Determine the final speed of the probe.

Attempt at solution:
I tried finding the acceleration by dividing the mass by the force. Then i tried subbing into the equation v^2=v^2+2ad

Is it correct because i get the same value as the original velocity?
 
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It sounds correct. You have a constant force, and thus a constant acceleration. Using the kinematic equation in your post, you should be able to find the final velocity. Don't forget to convert the km to meters.

Edit: By the way, you shouldn't get the same value as your initial velocity. A constant acceleration is taking place, and therefore your velocity is going to change.
 
You seem to have the correct method assuming that you don't need to take into account any mass lost. I would presume there is just a calculation error somewhere. If you post exactly what you're doing to get the wrong answer then perhaps someone can see where you made the mistake.
 
Have you converted the 86km into metres? It is impossible for v = u, as hotcommodity said, acceleration is occurring. I calculated, and v does not equal u. :smile:
 
Hot commity ,, u are a genius, it seemed that i wasn't converting the distance from kilometers to meters. It was right in front of me all along, Thanks for the help all, i really appreciate it ... another thing that's bothering me is this question:

A student a compressed spring of force constant 22 N/m to shoot a 7.5*10^-3 kg eraser across a desk. The magnitude of the force of friction on the eraser is 4.2*10^-2. How far along the horizontal desk will the eraser slide if the spring is initially compressed 3.5cm?

Attempt ---> I am thinking something along the line of Fd=1/2kx^2 but i seem to get stuck

any ideas
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
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