# Tutor profile: Siena S.

## Questions

### Subject: Physics (Newtonian Mechanics)

A car with a mass of 500kg starts off at rest initially, and then accelerates at 2m/s^2 for 16 seconds. What is the kinetic energy of the car at time t = 16seconds?

Initial velocity is zero, since it starts out at rest. Next, in order to find the final velocity at t = 16seconds, use the kinematics equation, vf = vi + a*t. Substituting in what we know: vf = 0 + (2m/s^2)*16 seconds = 32m/s. Lastly, use the Kinetic energy formula, KE = 1/2*m*v^2 KE = 1/2*(500kg)*(32m/s)^2 = 256,000J = 256KJ

### Subject: Basic Math

Convert 25min and 16 seconds into seconds

Since there are 60 seconds in 1 minute, multiply 25 min. by 60 sec. per 1 min, to cancel out the minutes and convert to seconds: 25min * (60sec/1min) = 1500seconds. Then add the original 16 seconds to it: 1500 + 16 = 1516 seconds.

### Subject: Civil Engineering

How do you find an internal force of a member of a truss using the Method of Sections?

First, you must use Equilibrium and solve for the sum of the forces in the x and y direction to solve for the reactions at the supports. Next, "cut" through the member in which you are trying to find the internal force of. Draw the forces of each member that has been cut through. Sum the moments about the point where more than 2 forces go through; that will give you the internal force of one member. To find the other member forces, sum the forces in the x and y direction.

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