DLxX said:I need to know if my answer is correct for the following problem.
A 2.04 kg block slides down a ramp from a height of 4.77m. If friction does 20J or work, what is the speed at the bottom of the ramp?
I keep getting 9.7m/s. Is this correct?
I found the work with the W=Fd formula and then used that value for work in the formula W=Ekf - Eki (kinetic energy) (.5mv^2).learningphysics said:I'm not getting that. Can you show what you did?
DLxX said:I found the work with the W=Fd formula and then used that value for work in the formula W=Ekf - Eki (kinetic energy) (.5mv^2).
95.4? I found that using the Gravitation Potential Energy Formula since I don't know the velocity yet, and since the grav pot should be equal to the kin pot at the end. Right?dextercioby said:What would the KE be,if it hadn't been friction on the inclined plane...?
Daniel.
I did that and got the correct answer of 8.6m/s, but would one of you mind explaining the theory behind subtracting the force of friction from the Grav Pot Energy? Should I just think of it like Net force or something?learningphysics said:Ah, you didn't take friction into account.
You need to include the work done by gravity as well as work done by friction on the left hand side. Be careful with signs.
mgh-20 = Ekf - Eki
DLxX said:I did that and got the correct answer of 8.6m/s, but would one of you mind explaining the theory behind subtracting the force of friction from the Grav Pot Energy? Should I just think of it like Net force or something?
Work and energy are closely related concepts in physics. Work is the measure of the force applied to an object, multiplied by the distance it moves in the direction of the force. Energy is the ability to do work or cause change in a system.
To solve a work and energy problem, you must first identify the known and unknown variables. Then, use the appropriate formulas (such as W = F*d for work and KE = 1/2*m*v^2 for kinetic energy) to calculate the answer. Make sure to pay attention to units and use correct algebraic steps.
An easy work and energy problem typically involves a simple scenario with only a few variables and straightforward calculations. For example, a problem that asks for the work done by a constant force on an object moving a certain distance would be considered easy.
To check if your answer is correct, you can use the same formulas backwards to see if they yield the original values. You can also double-check your math and make sure you used the correct units. If you are still unsure, you can ask a teacher or classmate for assistance.
Some common mistakes to avoid when solving work and energy problems include mixing up units, using incorrect formulas, and not properly setting up the problem with known and unknown variables. It is also important to pay attention to the direction of forces and motion when calculating work and energy.