- #1
cukitas2001
- 63
- 0
Hi guys, in need again for some help...thanks to everyone who helped before on my previous thread on potential energy i understand it a little better now. again I am stuck on three problems if you guys could provide me some insight i'd greatly appreciate it.
1) Sliding in socks. Suppose that the coefficient of friction between your feet and the floor, while wearing socks, is 0.250. Knowing this, you decide to get a running start and then slide across the floor. If your speed is 3.00m/s when you start to slide, what distance will you slide before stopping?
Ok i have no idea where to even begin with this one but i know it has to be simple but I am no seeing it? where can i begin?
2) The Great Sandini is a circus performer with mass 60.0kg who is shot from a cannon (actually a spring gun). You don't find many men of his caliber, so you help him design a new gun. This new gun has a very large spring with a very small mass and a force constant of 1400N/m that he will compress with a force of 4900N. The inside of the gun barrel is coated with Teflon, so the average friction force will be only 32.0N during the distance of 4.30m that he moves in the barrel.
Ok on this one i began by using hooke's law and getting the distance the spring would be compressed so 4900N/(1400N/n)=3.50m
Now i jumped into Ki+Ui+Wother=Kf+Uf
(1/2)60(0)^2+(1/2)1400(3.50)^2+32*4.30=(1/2)*60*vf^2+60(9.8)(2.9)
the vf i got was 15.3 but its comming out wrong. Anyone see where I am goin' wrong here?
3) A projectile of mass 20.5kg is fired at an angle of 58.0 degrees above the horizontal and with a speed of 85.0m/s. At the highest point of its trajectory the projectile explodes into two fragments with equal mass, one of which falls vertically with zero initial speed. You can ignore air resistance. How far from the point of firing does the other fragment strike if the terrain is level?
Ok so first i broke down the velocity into x and y components:
Vx=85cos(58)=45.0m/s and Vy=85sin58=72.1m/s
then i calculated the time it took to reach the highest point using Vf=Vi+at where i used 0=-9.80t+72.1, t=7.36s. I calculated the highest point to be at 265m and the x distance to be 331m using x=45(7.36)
Now i went to momentum. I found Vx to be 85m/s and using that i did the following: 85*7.36+331= 957m. I entered this answer and it says I am close but not there yet...what am i doing wrong?
thanks for any help in advance
1) Sliding in socks. Suppose that the coefficient of friction between your feet and the floor, while wearing socks, is 0.250. Knowing this, you decide to get a running start and then slide across the floor. If your speed is 3.00m/s when you start to slide, what distance will you slide before stopping?
Ok i have no idea where to even begin with this one but i know it has to be simple but I am no seeing it? where can i begin?
2) The Great Sandini is a circus performer with mass 60.0kg who is shot from a cannon (actually a spring gun). You don't find many men of his caliber, so you help him design a new gun. This new gun has a very large spring with a very small mass and a force constant of 1400N/m that he will compress with a force of 4900N. The inside of the gun barrel is coated with Teflon, so the average friction force will be only 32.0N during the distance of 4.30m that he moves in the barrel.
Ok on this one i began by using hooke's law and getting the distance the spring would be compressed so 4900N/(1400N/n)=3.50m
Now i jumped into Ki+Ui+Wother=Kf+Uf
(1/2)60(0)^2+(1/2)1400(3.50)^2+32*4.30=(1/2)*60*vf^2+60(9.8)(2.9)
the vf i got was 15.3 but its comming out wrong. Anyone see where I am goin' wrong here?
3) A projectile of mass 20.5kg is fired at an angle of 58.0 degrees above the horizontal and with a speed of 85.0m/s. At the highest point of its trajectory the projectile explodes into two fragments with equal mass, one of which falls vertically with zero initial speed. You can ignore air resistance. How far from the point of firing does the other fragment strike if the terrain is level?
Ok so first i broke down the velocity into x and y components:
Vx=85cos(58)=45.0m/s and Vy=85sin58=72.1m/s
then i calculated the time it took to reach the highest point using Vf=Vi+at where i used 0=-9.80t+72.1, t=7.36s. I calculated the highest point to be at 265m and the x distance to be 331m using x=45(7.36)
Now i went to momentum. I found Vx to be 85m/s and using that i did the following: 85*7.36+331= 957m. I entered this answer and it says I am close but not there yet...what am i doing wrong?
thanks for any help in advance