It will begin to roll due to the friction with the ground. There are no other forms of potential energy such as spring or electric that need to be considered in this problem. At the bottom of the incline, the rock is not only moving translationally but it is also rotating. Therefore, KE 2 includes both translational and rotational terms.
Height was chosen to be zero at the bottom of the hill, so there is no potential energy there. If you included a mgh term, that is fine. You will just set it to 0 in the next step. The moment of inertia of an object depends on the mass of the object and on how that mass is distributed. In this case, I assumed that the rock is spherical, and looked up the moment of inertia for a solid sphere.
Make sure you don't use moment of inertia of a shell, which means a hollow object. If you assumed a different solid shape, such as a cylinder, that is fine as long as you work the problem in the same way.
The sign of gravitational potential energy comes from the sign of h. Therefore, make sure to use a positive value for g. In this case, m was not present in all terms.
The W nc term does not directly contain mass and so it cannot be divided out. In order to cancel a variable, it must be present in every term in an equation.
A non-conservative force is any force that takes energy in or out of the system. In this part of the problem, you are asked to calculate how much drag is required to take energy out of the system. The work done by any force F is equal to that force times the distance over which it acts, times the sine of the angle between the force and the direction of motion. Drag acts against the motion of an object. Therefore, -W nc is overall positive. This makes sense: if energy leaves the system, that amount of energy must be added to the final energy of the system in order to account for all of the initial energy.
The distance over which a non-consevative force acts is measured along the path of the motion. You want to use the path of the rock and not just the height. If no drag force is present, the initial kinetic and gravitational energies of the rock remain in the system and are converted into translational and rotational kinetic energies. Active Oldest Votes. Improve this answer. Tofi Tofi 2, 10 10 silver badges 21 21 bronze badges. This does not seem correct. At the end of the first 25 m the bolder has a velocity of In the second 25 m its rotational energy doesn't change any more but its translational energy does.
Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. A hollow sphere such as an inflatable ball A solid sphere such as a marble It does not need to be the same size as the hollow sphere.
Cardboard box or stack of textbooks Flat, rigid material to use as a ramp, such as a piece of foam-core poster board or wooden board. The longer the ramp, the easier it will be to see the results. Preparation Empty, wash and dry one of the cans. Prop up one end of your ramp on a box or stack of books so it forms about a to degree angle with the floor Procedure Hold both cans next to each other at the top of the ramp.
Which one do you think will get to the bottom first? Let go of both cans at the same time. Watch the cans closely. Which one reaches the bottom first? Repeat the race a few more times.
Does the same can win each time? Now try the race with your solid and hollow spheres. Which one do you predict will get to the bottom first? What happens when you race them? Extra: Find more round objects spheres or cylinders that you can roll down the ramp. For example, rolls of tape, markers, plastic bottles, different types of balls, etcetera.
Try racing different types objects against each other. Test yourself. Join Study Groups. Create your own study plan. Join live cram sessions. Live student success coach. Zachary M. Hope College. Aspen F. University of Sheffield. Meghan M. McMaster University. Physics Mechanics Bootcamp Lectures Math Review - Intro In mathematics, a proof is a sequence of statements given to explain how a conclusion is derived from premises known or assumed to be true. Algebra - Example 1 In mathematics, algebra is one of the broad parts of mathematics, together with number theory, geometry and analysis.
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