Question

Mrs. Smith does her daily chores. She walks 5 m to the laundry room and then turns around and walks -14 m to the kitchen. The whole process takes her 11 minutes. What was her average velocity for these events?
1.48 m/s
0.212 m/s
-0.136 m/s
-0.0075 m/s

A spy is running across the bridge of an aircraft carrier. The spy is moving with a velocity of - 4 m/s relative to the carrier. However, the aircraft carrier is moving with a velocity of 12 m/s. There is a person standing stationary on a beach watching the event. What will be the velocity of the spy according to the person on the beach?
8 m/s
6 m/s
-4 m/s
-7 m/s

Answer 1

Answer:

Explanation:

Velocity vs speed and distance vs displacement is a pretty important.  Distance and speed have no direction while displacement and velocity have a direction.

In other words, taking the first example, going 5m one way and then 14 the other would make the total distance 19m, while displacement would be -9m from where you started.  

Anyway, velocity is displacement divided by time.  For the first one I already got that the displacement is -9m, and the time is 11 minutes.  It's worth noting that the answers are all in m/s, so we should convert the minutes to seconds.  To do that multiply 11 minutes by (60 seconds/1 minute) so the minutes cancel out.  so 11*60 is 660 seconds.  Now, to find velocity we just divide.  -9m/660s = -.0136 Which... doesn't seem to be one of the options...

For the second part it gives two point of views.  If you were standing on the carrier, the spy would look like it was moving  4 m/s away from you, but the carrier itself is moving 12 m/s in the positive direction to an onlooker.  If it's hard to figure out try thinking what it would look like if the spy was just standing still.  it would look like they were moving -12 m/s if you were standing on the carrier.  Then if the spy was moving at say 1 m/s it would look like they were moving -11 m/s if you were standing on the carrier.  

Just keep that line of reasoning , where if it looks like the spy is moving -4 m/s from the carrier then the spy is moving 4 m/s slower than the carrier, so the spy is moving at 8 m/s

Pretty sure I got the first part right, so maybe a misprint from the question?