# Engineering systems

• Jul 26th 2012, 05:40 AM
xsokyx
Engineering systems
A crate of mass 1500kg is at the top of a frictionless ramp. The slope of the ramp is 15degrees to the horizontal and is 75 metres long. The weight is about to slide down the ramp, what is the velocity at the bottom of the ramp?
• Jul 26th 2012, 06:51 AM
skeeter
Re: Engineering systems
Quote:

Originally Posted by xsokyx
A crate of mass 1500kg is at the top of a frictionless ramp. The slope of the ramp is 15degrees to the horizontal and is 75 metres long. The weight is about to slide down the ramp, what is the velocity at the bottom of the ramp?

use energy principles ...

potential energy at the top of the ramp = kinetic energy at the bottom of the ramp

$\displaystyle mgh = \frac{mv^2}{2}$
• Jul 26th 2012, 08:58 AM
xsokyx
Re: Engineering systems
could you explain to me how to complete the formula, or tell me what mgh etc means?
• Jul 26th 2012, 10:10 AM
HallsofIvy
Re: Engineering systems
"m" is the mass of the object (which isn't really relevant here since the two "m"s in the formula will cancel), "g" is the acceleration due to gravity, at the surface of the earth, about 9.81 meters per second per second. "h" is the vertical height between the initial position of the object and the last position (the "opposite side" of a right triangle with hypotenuse the length of the ramp). v is the velocity (in meters per second if you use g= 9.81) of the object at the bottom of the ramp (what you are asked to find).
• Jul 26th 2012, 10:59 AM
skeeter
Re: Engineering systems
Quote:

Originally Posted by xsokyx
could you explain to me how to complete the formula, or tell me what mgh etc means?

What do you know about the dynamics of objects sliding down frictionless incline planes? You obviously are not schooled in the principles of mechanical energy ... have you studied kinematics and Newton's laws of motion?
• Jul 27th 2012, 02:35 AM
xsokyx
Re: Engineering systems
What I really need is someone that can help with solving the equation. I understand a bit about newtons laws of motions. I can find that out else where, all I need is help on the equation, that's why I came here.
• Jul 27th 2012, 04:50 AM
skeeter
Re: Engineering systems
Quote:

Originally Posted by xsokyx
What I really need is someone that can help with solving the equation. I understand a bit about newtons laws of motions. I can find that out else where, all I need is help on the equation, that's why I came here.

$\displaystyle mgh = \frac{mv^2}{2}$

basic algebra solving for $\displaystyle v$ ...

$\displaystyle v = \sqrt{2gh}$

using right triangle trig ...

$\displaystyle h = 75\sin(15^\circ) \, meters$

$\displaystyle g = 9.8 \, m/s^2$

... finish it.

Note that you didn't provide an equation to solve the given problem in the first place. Understand that when someone posts a problem in the advanced applied math forum, folks here are going to assume that the poster has the minimum requisite knowledge to at least attempt setting up their own equation based on the problem statement.