Physic questions,please help?

Question

1.A small mailbag is released froma helicopter that is descending steadily at 1.50m/s. after 2.00s,(a)what is the speed of the mailbag, and (b) how far is it below the helicopter? (c) what are your answers to parts (a) and (b) if the helicopter is rising steadily at 1.5m/s?

2.A surveyor measures the distance across a straight river by the following method: starting directly across from a tree on the opposite bank, she walks 100 m along the riverbank to estabilish a baseline. then she sights across to the tree. the angle from her baseline to the tree is 35.0 degree. how wide is the river?

3. A dog searching for a bone walks 3.5 m south, then 8.2 m at an angle 30.0 degree north of east,and finally 15.0 m west. find the dog's resultant displacement vector,using graphical techniques.

Answer 1

I'm not going to do your homework for you, but i will help. :)

1. (a and b)Basic kinematics:

vi = 1.5m/s (initial velocity)

vf = ? (final velocity)

a = 9.8 m/s^2 (acceleration (due to gravity))

d = ?

t = 2s (time)

formulas

a = (vf - vi)/t

s = vit - .5a(t^2)

(c) same thing but initial velocity is negative

2. it easy if its is visualized correctly.

draw the picture out, (of a rt triangle with one side 100m and one angle 35 degrees). Then use trig

3. Just draw it out, and use trig. Displacement is the distance from the beginning, not the distance moved

Hope it helped

Answer 2

1)  (a)V (vertical) will only be considered in this question as the horizontal speed of the copter is not given.

so use ,v =u + at  (a = +g)

  hence,v = 0 + 1.5*2

            v = 3 m/s

(b) use eq. s = ut + 1/2at^2 for calc. distance after 2 sec.

(c) first calc. u for the bag then apply the above eqn.

2) use- tan 35 = (width of river)/100

so, width of river = 70.02m.

3) ..~i cant draw a graphical representation of vector addn.~

  but the solution will be the resultant of vector 3.5 & 8.2 with an angle of 30 degrees betn. them & then add/subtract(depending upon the sign u hav taken) the vector 15 m