Friday, April 8

In class we looked over the Review from yesterday as well as the the questions on p 213 in the green text book.

Questions 1-5, and 17 -19

1.
W= F*D
W= 80N * 10m
= 800J

2. d= 8m
F = mg
= 150kg * 9.8m/s2
=1470N
W=FD
=1470N*8m
=11760J

3.
w=176J
d= .300m
F=W/D
= 176/.3
= 586.67

m = 586.67/ 9.8
= 59.9kg

4.
W=FD
= (2.25 x 10 3N)(7.50)
= 1.60 x 10 4 J

m=dv
=( 2.00 x10 3 kg/m3)(1.15m3)
m=2.30 x 10 3 kg
Fg=mg = ( 2.3 x 10 3 kg)(9.8m/s2)
= 2.25 x10 3 N
totally Fg = 2.25 x 10 4 N + 2.25 x 103 N
= 2.48 x10 4 N

5.
W=FD
=(3N)(.16m)
= .48J
total .080J

W= 1/2 FD
= 1/2( 4N)(.10m)
=.32J

answers for 17-19

17
a. W= 5527.7J
b. 0 work is done.
c. W= -5527.2J
d. No, doesn't exert the force
e. W = 2352.0N
P = 2.2 x 10 3 watts

18.
a. W= 9 x 10 3 J
b. p .3 x 10 3 W

19.
a. P= 3.44 watts
b. P= 696 watts

lab was also due today.