Physics - September 2007

Tension in a string from which a 4.3 kg object is suspened in an elevator is equal to 45N.

What is the magnitude of the acceleration of the elevator?
What is its direction? (I don't know how I would go about answering this question)


m=4.3kg
T=45N
g=-9.8

F=ma=T-mg
a=T-mg/m
a=(45-42.14)/4.3
a=.66512 m/s^2

IS this correct??

2007-09-23 12:39:06 · 1 answers · asked by ? 1

if , instead of letting the ball on the end swing and hit the others, someone shot the end ball of a stationary newton's cradle[those things ,sometimes as toys, with hanging metal balls in a row]how [assume without destroying it]would it behave?

2007-09-23 12:35:52 · 1 answers · asked by Anonymous

You're 5.0from one wall of a house. You want to toss a ball to your friend who is 5.0 fromthe opposite wall. the throw and catch each occur 1m above the groiund.
a. what minimum speed will allow the ball to clear the roof
b. at what angle should you toss the ball.

2007-09-23 12:33:55 · 1 answers · asked by vadawa13 3

2007-09-23 11:31:38 · 3 answers · asked by MoPleasure4U 4

Vector A has x and y components of -20 cm and 12 cm, respectively; vector B has x and y components of 4.79 cm and -20 cm, respectively.

a - If A-B+3C=0, what is the x component of C? Answer in units of cm.

b - What is the y component of C? Answer in units of cm.


I got Cx to be -15.21cm and Cy as -8...but bringing it back that equation doesnt equal 0..unless I did something wrong.

2007-09-23 10:59:28 · 1 answers · asked by grouchy187 2

2007-09-23 10:49:20 · 5 answers · asked by Anonymous

HELPPPPPPPPPPP AHHHHHHHHHHHHHHHHHHHHHHHHHHHHh

2007-09-23 09:54:21 · 1 answers · asked by Shawn Carter 1

2007-09-23 09:53:01 · 10 answers · asked by varghese p 3

THe acceleration of grav is 10m/s².
WHat is the greatest acceleration a runner can muster if the friction between her shoes and the pavement is 74% her weight?
Answer in m/s².

THANK YOU VERY MUCH

2007-09-23 09:51:41 · 1 answers · asked by Ghost Eye 1

2007-09-23 09:50:29 · 4 answers · asked by varghese p 3

A 6-kg bucket of water is being pulled straight up by a string. The upward acceleration of the bucket is constant, with magnitude of 3 m/s^2.

The tension in the rope is then?

Now assume the bucket is accelerating downward, with magnitude 3 m/s^2.

The tension in the rope is then?

I need some help with this problem. Newton's Laws have really confused me. Any help would be great. Thanks!

2007-09-23 09:50:13 · 1 answers · asked by Anonymous

what effect does this have on the velocity of the emerging bullet? Why do long range cannons have such long barrels?

2007-09-23 09:33:04 · 4 answers · asked by kntagler 1

.....with long wavelengths?

2007-09-23 09:22:07 · 5 answers · asked by :] 3

The coefficient of static friction between the m = 3.10 kg crate and the 35.0° incline of Figure P4.41 is 0.340. What minimum force must be applied to the crate perpendicular to the incline to prevent the crate from sliding down the incline?
http://www.webassign.net/sercp/p4-41alt.gif

2007-09-23 09:21:30 · 1 answers · asked by Bill 1

2007-09-23 09:17:02 · 3 answers · asked by firemama 1

You are rollerblading at a constant 4.5m/s, you reach a down hill and start to accelerate at 2.65 m/s for the next 70meters. What is your final velocity? How long does it take to go the 70 meters.?
thanks in advance, and explain how u got it!

2007-09-23 09:12:48 · 1 answers · asked by Anonymous

A vehicle is cruising at 18.0 m/s it speeds up uniformly at 4 m/s^2 for the next 46 meters. What is the final velocity in m/s?

Given: a=4 m/s^2 d=46m Vi= 18.0 m/s

Equation: (Vf^2) = (Vi^2) + (2AD)

Solution: (Vf^2) = (18 m/s)^2 + 2 ( 4 m/s)^2 (46 m)

So final velocity = about 42 m/s (?)

2007-09-23 09:12:39 · 1 answers · asked by Katie E 2

HELPPP PLEASEE NOWWWW

2007-09-23 09:10:43 · 5 answers · asked by Shawn Carter 1

0.050kg mass moves on the end of a spring with k=25 N/m and is acted on by a damping force F=-bv. It is initially displaces at 0.3 m and the amplitude decreases to 0.1 m in 5 sec. What is magnitude of damping constant b?

2007-09-23 08:59:08 · 1 answers · asked by coo1mints 3

2007-09-23 08:57:30 · 7 answers · asked by Derek A T 1

Jean, who likes physics experiments, dangles her watch from a thin piece of string while the jetliner she is in takes off from the airport. She notices that the string makes an angle of 24° with respect to the vertical while the aircraft accelerates for takeoff, which takes about 17 seconds. Estimate the takeoff speed of the aircraft.

=..............m/s

2007-09-23 08:30:41 · 3 answers · asked by Nikita 1

The second law of thermodynamics stated that everything is headed for entropy. Therefore whatever you create will be of a lower form of order. Which then beggs the question: Should you create nothing in order to preserve, or is your version of order an important part of chaos.

2007-09-23 08:13:23 · 2 answers · asked by Kelly 3

Sound travels at a speed of 340 m/sec. The lowest pitch a human can hear is about 20 Hz. How long is the wave length of a 20 Hz sound wave? Show the set up with units. Please answer this, I really need help.

2007-09-23 07:43:47 · 3 answers · asked by ... 2

You can think of the work-kinetic energy theorem as a second theory of motion, parallel to Newton's laws in describing how outside influences affect the motion of an object. In this problem work out parts (a) and (b) separately from parts (c) and (d) to compare the predictions of the two theories. In a rifle barrel, a 15.0 g bullet is accelerated from rest to a speed of 740 m/s. (a) Find the work that is done on the bullet in kJ. (b) If the rifle barrel is 70.0 cm long, find the magnitude of the average total force that acted on it, as F = W / (r cos ) in kN. (c) Find the constant acceleration of a bullet that starts from rest and gains a speed of 740 m/s over a distance of 70.0 cm in km/s^2. (d) If the bullet has mass 15.0 g, find the total force that acted on it as F = ma in kN.

2007-09-23 07:16:22 · 1 answers · asked by green 1

There is a 1500 kg boat that's bobbing up and down in the waves in a lake, while its tied. The amplitude for its simple harmonic motion is 20 cm and the period is 3.5 s. When the boat is at its highest point, its deck is at the same height as the stationaty dock. A man (60 kg) is on the boat, and he wants to leave the boat when it is within 10 cm of the dock level. How much time does he have to board the boat comfortably during each cycle of up-and-down motion?

2007-09-23 06:09:58 · 1 answers · asked by Wolfgang M 1

A subway train starting from rest leaves a station with a constant acceleration. At the end of 5.59 s, its is moving at 9.9502 m/s. What is the train's displacement in the first 4.26517 s of motion? Answer in units of m.
When I used the formula d = v1t + 1/2at^2 I got 27.81 m which turns out to be the wrong answer. Please help!

2007-09-23 06:08:49 · 2 answers · asked by jon s 2

...that has been able to see images as small as atoms, although barely visibly. Does anyone know where I'd be able to see any pictures they took of them?

2007-09-23 05:37:14 · 1 answers · asked by J 2

A 4 hp lawnmower engine moves with a force of 1,492 N over a distance of 100.0 m. How much time did this require?

2007-09-23 05:32:58 · 1 answers · asked by Anonymous

I got the other ones and everyone helped a lot, I'm very grateful...anyway, last one of the day..

A ball is thrown straight up and returns to the thrower's hand after 3s in the air. A second ball if thrown at an agle of 37 degrees with the horizontal. The acceleration of gravity is 9.8 m/s^2.

At what speed must the second ball be thrown so that it reaches the same height as the one thrown vertically? Answer in units of m/s.

2007-09-23 05:27:53 · 1 answers · asked by MD12 2

if it can be measured we must know what it is?and how to alter it, ie anti gravity?

2007-09-23 04:59:32 · 4 answers · asked by strongbow 3