Tuesday
May 5, 2015

Homework Help: physics

Posted by mary on Wednesday, June 27, 2012 at 4:41am.

1. A yacht is tacking into the wind on a zigzag path. On the rst leg of the course, the yacht has a
displacement of 12 km at 840 north of east. After a second leg has been completed, the yacht's resultant
displacement is 10 miles at 230 west of south. Determine the magnitude and direction of the second leg
of the course.
2. A ferry boat crosses a 550-m wide river from the east to the west shore in 1 min and 9 s. (a) What is the
boat's average velocity? (b) The boat makes the return trip 500 m in 58 s. What is the boat's average
velocity for the return trip? (c) What is the boat's average speed for the entire round trip? What is the
boat's average velocity for the entire round-trip?
3. Suppose a gazelle is capable of accelerating from rest to its top speed of 25 m/s in a distance of 50 m
and, after attaining its speed, the animal can maintain it for an extended period of time. In addition,
suppose a cheetah can accelerate from rest to its top speed of 30 m/s in a distance of 60m, but then
can maintain this speed for only 4.0 s before it must give up the chase. How close to a gazelle must a
cheetah be before it can launch a successful attack?
4. A student throws a set of keys vertically upward to her sorority sister, who is in a window 4.00 m above.
The keys are caught 1.50 s later by the sister's outstretched hand. (a) With what initial velocity were
the keys thrown? (b) What was the velocity of the keys just before they were caught?

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