# Did I do this question correctly?

izelkay

## Homework Statement

http://cyclotron.tamu.edu/dhy/sample_exam1_phys218.pdf [Broken]

For Number 2 Part a

v0 = 1.7 m/s
F = ma
v = 0m/s
v² = v0² + 2aΔx

## The Attempt at a Solution

Spent like 30 minutes trying to use a constant acceleration kinematics equation, but nothing seemed to work without knowing either the time or the acceleration.
Then I remembered that F = ma, and the problem gave me the force (9.8*10^4N) and the mass (3.6*10^7kg). So I solved for a, and got -0.00272 m/s².

I plugged this acceleration into v² = v0² + 2aΔx and solved for Δx, and I got 530.82 meters. Is this correct? If not, can anyone help me understand what I did wrong?

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Homework Helper
Gold Member
Looks good!

izelkay
For C of that question, would I use the final velocity I obtained from part b as the new initial velocity, and 0 as the final velocity, solve for acceleration using v² = v0² + 2aΔx (Δx being 1.5m), and multiply that acceleration by the mass of the tanker?

Homework Helper
Gold Member
That sounds good, too. Or, you could use work and energy concepts if you're familiar with them.

izelkay
Awesome; thanks. We haven't gotten to the work and energy stuff yet.

Homework Helper
Gold Member
OK. Good work!