- #1

paulimerci

- 287

- 47

- Homework Statement
- A four man bob sled team each push on the bobsled with a force of 25N. The first bob sledder pushes for 3 secs, the second for 4 secs, the third for 5 secs and the fourth one for 6 secs. What is the total impulse the bobsledders exerted on the bobsled? supposing the bobsled has a mass of 45kg, what is the final velocity of the bobsled after the last bobsledder jumps in?

- Relevant Equations
- Impulse and change in momentum

For calculating the total impulse, I'm taking the individual impact force times the elapsed time and adding them all together to get the total impulse. Given F = 25N, ## \Delta t_1 =3 secs##, ##\Delta t_2 = 4secs##, ## \Delta t_3 = 5secs##, ## \Delta t_4 = 6secs##.

$$ Impulse 1 = F \Delta t_1 $$

$$ = 25 \cdot 3 $$

$$ = 75 Ns $$

$$ Impulse 2 = F\Delta t_2$$

$$ = 100 Ns $$

$$ Impulse 3 = 125 Ns$$

$$ Impulse 4 = 150Ns$$

Total impulse = Impulse 1+ Impulse 2+ Impulse 3 + Impulse 4

= 450Ns.

For the second part of the problem, I'm unsure whether I should consider the bobsled at rest or in motion when all three sledders are in it. And it looks way more complicated because individual masses of sledders are not provided.

And the answer to the above is not correct. Can anyone help me solve this problem?

$$ Impulse 1 = F \Delta t_1 $$

$$ = 25 \cdot 3 $$

$$ = 75 Ns $$

$$ Impulse 2 = F\Delta t_2$$

$$ = 100 Ns $$

$$ Impulse 3 = 125 Ns$$

$$ Impulse 4 = 150Ns$$

Total impulse = Impulse 1+ Impulse 2+ Impulse 3 + Impulse 4

= 450Ns.

For the second part of the problem, I'm unsure whether I should consider the bobsled at rest or in motion when all three sledders are in it. And it looks way more complicated because individual masses of sledders are not provided.

And the answer to the above is not correct. Can anyone help me solve this problem?