# Tutor profile: Marshall F.

## Questions

### Subject: Physics (Newtonian Mechanics)

A person is pushing a 20kg block on the ground with a force of 200 newtons. The coefficient of friction between the block and the ground is 0.3. What is the horizontal acceleration of the block. assuming the block is just starting to move.

1: Find the normal force on the box from the ground. Find the weight of the block(mass*acceleration(gravity): 9.8*20=196 kg*m/s^2=196 N=Fn *note: the normal force equals the weight of the block as it is not on an angle. 2: Find the force of friction Friction=Fn*coefficient of friction=0.3*196=58.8N 3: Find sum of forces Only two forces acting horizontally, friction and the pushing force. These forces are in opposite directions. 200-58.8=141.2N 4: Find the acceleration Acceleration=Force/mass=141.2/20=7.06 m/s^2

### Subject: Calculus

Evaluate the integral of xe^(5x)

For this question you must use integration by parts! This is done by defining one component as u, and the other as dv. For this equation, we will set x as u and e^(5x) as dv. So, using simple derivations/integrations we see that du=derivative(x)=1, and v=integral(e^(5x))=e^(5x)/5. From this, we will use the equation Integral(u*dv)=u*v-Integral(du*v). Then, plugging in we get x*e^(5x)/5-Integral(e^(5x))/5*1), which simplifies to xe^(5x)/5-e^(5x)/25!

### Subject: Materials Science

How would you perform a 3D analysis of chemical composition within ~1% accuracy of a conductive material.

Using Xray photoelectron spectroscopy. In order to get the depth profile you must bombard the sample with ions with zalar rotation in order to avoid mixing of layers. This will allow an accurate depiction of the materials composition throughout its depth. This is helpful for applications like electronics.

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