QUESTION 1 You and a friend are measuring a field for an ecology experiment. You

Question

QUESTION 1

You and a friend are measuring a field for an ecology experiment. You walk due east at a speed of 1.0 m/s and your friend moves in a direction 30o east of north at a speed of 0.9 m/s. Both of you walk for 85 seconds when you simultaneously stop.

At the end of the walk, how far from your friend are you?

Give your answer in meters.

QUESTION 2

Consider the following motion in one dimension, the x-direction. Starting from rest at x = 0 you accelerate for 7.4 seconds at 4.1 m/s2 and then accelerate for 2.8 seconds at -0.7 m/s2. What is your final position?

Give your answer in meters.

QUESTION 3

In your internship with the Mythbusters, you are helping measure the velocity of a frozen turkey shot out of an air cannon. Your high-speed camera shows position of the turkey and the time, the times being measured from the time the turkey leaves the cannon and the position being measured from some unimportant position. Using the video, you measure the position of the turkey to be x = 0.90 m at t = 0.008 sec, and then measure the position of the turkey to be x = 5.65 m at t = 0.071 sec.

Assuming the velocity is constant over this time, what is the turkey’s velocity?

Give your answer in units of m/s.

QUESTION 4

Consider a police car catching you from behind to pull you over for speeding.

You are driving at a constant velocity of 37.0 m/s.

When it is 60 m behind you and moving with a velocity of 48.0 m/s, the police car starts to slow down. The police need to have the same velocity as you when they catch you.

What acceleration must the police car have so that its velocity matches yours when it catches up to you?

Give your answer in m/s2.

Explanation / Answer

1) In the E-N coordinate system, final position vectors of you (A) and your friend (B) are:

A = 85 E

B = (85 * 0.9 * sin30o) E + (85 * 0.9 * cos30o) N = 38.25 E + 66.25 N

Separation vector is given by,

A - B = (85 - 38.25) E - 66.25 N = 46.75 E + 66.25 N

Distance between A and B = (46.752 + 66.252)1/2 = 81.1 m

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