Physics - September 2007

The tallest Sequoia sempervirens tree in California's Redwood National park is 111 m tall. Suppose an object is thrown downward from the top of that tree with a certain initial velocity. If that object reaches the ground in 3.80 s, what is the object's initial velocity?

2007-09-22 11:25:01 · 3 answers · asked by Anonymous

The gravitational potentials due to the spherical mass are all negative values. However, when the spherical mass is electrically charged, explain why the electrical potentials can be positive values with reference to the defintition of potentials.

2007-09-22 11:15:46 · 4 answers · asked by Anonymous

1 )A jet plane is cruising at 300 m/s when suddenly the pilot turns the engines up to full throttle. After traveling 4.0 km, the jet is moving with a speed of 400 m/s. What is the jet's acceleration, assuming it to be a constant acceleration?

2)A plane accelerates from rest at a constant rate of 5.00 along a runway that is 1800 long. Assume that the plane reaches the required takeoff velocity at the end of the runway. What is the time needed to take off?

2007-09-22 10:31:52 · 4 answers · asked by Anonymous

decreasing according to the equation P = Qe^(-kt), where t represents time in hours. If 10% of the pollution is removed in the first five hours:
(a) What percentage of the pollution is left after 15 hours?
(b) How long will it take before the pollution is reduced to 10%?

2007-09-22 10:30:28 · 1 answers · asked by simonkf2002 1

2007-09-22 10:14:23 · 2 answers · asked by   4

Let us think about that for a minute or so. It must have taken a lot energy for that to have happenned. this is really more than one question. what made everything come together? why didn't the particules continue going far apart. If gravity was strong enough to stop it than won't it been strong enough to stop it before it even got started?

2007-09-22 10:13:44 · 4 answers · asked by Anonymous

Two forces, 381N at 8deg. & 307N at 25deg. are applied to a car in an effort to accelerate it.?
What is the magnitude of the resultant of
these two forces?

What is the direction of the resultant force (in re-
lation to forward, with counterclockwise con-
sidered positive)?????
within the
limits of -180deg to 180deg

2007-09-22 10:08:19 · 3 answers · asked by ? 1

I'm just starting Physics this year. We have a lab where we collected data of a falling object.

Here is my graph of displacement vs time squared.
http://i5.photobucket.com/albums/y182/luvlaws/graph.gif?t=1190494426 (Ignore the black 'best fit' line).

I'm trying to figure out "what the shape of the graph indicates" and "the significance of the slope of the graph".

I've never come across a graph with time squared before.

My answer is that the falling object accelerates downwards until it hits the velocity -9.8 m/s (gravity)? So the curve in the beginning is the acceleration; the rest of the graph is more straight, meaning constant velocity as the object falls?

Is this right?
Thanks a ton if you can help.

2007-09-22 10:06:36 · 4 answers · asked by Paul 3

Arlene is to walk across a high wire strung horizontally between two buildings 13.0 m apart. The sag in the rope when she is at the midpoint is 10.0°. If her mass is 58.0 kg, what is the tension in the rope at this point?.....N

2007-09-22 09:50:31 · 3 answers · asked by Nikita 1

its for my homework i need to describe the properties and a typical application of a liquid electricl insulator

Plz help !!!!!!

2007-09-22 09:06:45 · 6 answers · asked by Anonymous

I keep trying to think of ways to answer this question but it just isn't working. Can anyone help me out or give me some hints or ideas?

We usually treat a frame of reference attached to the earth as an inertial frame. This is in fact not true. Describe an experiment you could do, using material one is likely to find in the store rooms under the Physics Lecture Hall (i.e., what might be used for classroom demonstrations), which would show that the Physics Lecture Hall itself is NOT an inertial frame.

thanks for your help!

2007-09-22 09:00:41 · 3 answers · asked by Dan O 1

An athlete executing a long jump leaves the ground at a 35° angle and travels 6.80 m.

takeoff speed is 8.31 m/s.

If this speed were increased by just 6.0%, how much longer would the jump be?

2007-09-22 08:51:27 · 2 answers · asked by oxblackout12 1

Is this a 2-way trip?....The way there and back....? Back to what?....What is the origin of light, and what does it return to?
When light, or any radiation, gets emitted, it ultimately gets absorbed. Could the return trip be that absorption trip....?
Is this the process that keeps space-time a Constant?

2007-09-22 08:49:52 · 6 answers · asked by starling 3

Can anyone explain whether this is a possible scenario or not and why?

thanks!

2007-09-22 08:20:51 · 5 answers · asked by sungirl 2

The acceleration function of a bus is given by a(t) = 1.2t

a.) derive the bus's velocity and position functions. Show all appropriate calculus and algebraic steps.

b.) if the bus's velocity at time t = 1.0 sec is 5.0 m/s, what is its velocity at time t = 2.0 sec?

c.) if the bus's position at time t = 1.0 sec is 6.0 m, what is its position at time t = 2.0 sec?

After differenciating, i got
v = 2.4t^2 + vi
x = 4/5t^3 + vit + xi

are these right?, and if they are how would i find the next two answers?

plz show me your steps

2007-09-22 08:08:00 · 2 answers · asked by Alex M 1

How many MW (mega watts) does a nuclear power plant generate in a day and wat is the smallest nuclear power plant that can power a small city

2007-09-22 07:56:22 · 5 answers · asked by Tau dreadnaught 1

Let's just say that Dr.H has two glasses of water that are 100mL each. One is 80C and the other is 60C. What will be the stable temperature of the mixture when I pour them both in one container?

Is it:
a) 60C
b) 65C
c) 70C
d) 75C
e) I know that it's a number in between the two but I'm not sure how to calculate it.

2007-09-22 07:55:24 · 6 answers · asked by Dr. H(Relax!) 1

Say I go to a fast food restaurant 10 miles away to get lunch. I averaged 29 miles per hour on the way there. Anyway, I need my average speed to be 60 miles per hour for the whole round trip. How fast do I need to go on the way back?

Just say that I got the food in record time so it's negligible and time spent actually traveling is all that matters.

2007-09-22 07:46:07 · 5 answers · asked by Anonymous

A. the speed of the object as it falls is 9.8m/s.
B. the object falls 9.8 meters during the first second only.
C. derivative of the distance with respect to time for the object equals 9.8m/s^2.
D. speed of object increases 9.8 m/s during each second
E. object falls 9.8 meters during each second

I think its D

2007-09-22 07:41:59 · 3 answers · asked by XzoeyX 2

You plan a trip on which you want to average 90km/h. You cover the first half of the distance at an average speed of only 48km/h. What must your average speed be in the second half of the trip to meet your goal? Note that the velocities are based on half the distance, not half the time.

2007-09-22 07:21:14 · 3 answers · asked by Anonymous

science work sheet from school

2007-09-22 07:03:09 · 4 answers · asked by angeljade_95 1

For about 1 week I have been suffering with this obssesive thought and it will not go away. I'm only 16 and what the hell? My thought has concluded that as long as the universe exists why can't we live tell the end of that, because matter can not be created or distroied. It just so happens that what if you could keep the atoms you are made of intact for that long.

2007-09-22 06:37:51 · 6 answers · asked by Anonymous

transferred to the k.e of a stone wen the catapult is fired.

2)A skydiver of mas 70kg reaches a speed of 45m/s after falling 150m.by finding the loss of g.p.e and the gain in k.e.determine the work done on the skydiver by the push of the air and hence find the average vertical push of the air on him during the first 150m of his fall.
3)A supermarket troley of total mass 22kg is pushed up a ramp with a force of 14N.The ramp is 5.5m long and rises 0.35m.take g=10N/kg.If the speed of the trolley at the bottom of the ramp was 1.0m/s at the bottom of the ramp,what is its speed at the top.
Practice in physics Pg.40

2007-09-22 06:15:30 · 1 answers · asked by mba 1

Its for my science.

2007-09-22 06:06:19 · 7 answers · asked by H T 1

PLEASE explain

im only in 8th grade

it sais that in my homework

ppl say it does, so what do i write down??!?!?

2007-09-22 05:42:02 · 9 answers · asked by Yep! 1

Peter and Danny are standing opposite of one another on a carousel which is turning counterclockwise. Peter throws a ball directly towards Danny.

a) The ball gets to Danny.
b) The ball goes to the right of Danny.
c) The ball goes to the left of Danny.

2007-09-22 04:54:13 · 5 answers · asked by ? 6

1. In a 100 meter race Maggie and Judy cross the finish line in a dead heat, both taking 10.2 seconds. They both accelerated uniformly and Maggie took 2s and Judy took 3 to attain max. speed, which they maintained for the rest of the race. a)what was the acceleration of each. b)what were their max. speeds? c)which sprinter was ahead at the 6.0 second mark and by how much? 2. a jewel thief steals a golden egg from the third floor of an office building. Police enter and the thief runs to hide on an upper floor. To be free of the evidence, the thief drops the egg out the window. A detective on the 3rd floor sees the egg falling and times it as it passed the lower half of her window. The floors of the building are located 4 m apart. The egg took 0.101 s to fall 1.50 m past the lower part of the detective's window. The bottom of the detective's window is 8 m above the ground. On what floor is the thief hiding??
Anyone that can help I would really appreciate it. Thanks in advance!

2007-09-22 04:41:54 · 1 answers · asked by Anonymous

i have heard of sites that you can go on and look up your address and view your house from space, satalite whatever? is there a site and if so what is it

2007-09-22 04:19:50 · 7 answers · asked by Rhonda A 1

2007-09-22 04:06:44 · 3 answers · asked by Anonymous

Please explain fully, I just don't get the concept. Thanks all.

2007-09-22 04:06:34 · 2 answers · asked by Anonymous