Physics - November 2007

if you are pushing a lawnmower across the grass, can you increase the horizontal component of the force you exert on the mower without increaing the magnitude of the force?

2007-11-29 09:52:31 · 1 answers · asked by Aitu4 3

Ignoring air drag, what is the maximum speed possible for a horizontally moving tennis ball as it clears the net 1.0 m high and strikes within the court's border, 12 m distant?
in meters per second

2007-11-29 09:48:27 · 1 answers · asked by joe s 1

1. Why does an automobile moving at constant velocity have to keep burning fuel to maintain motion?


2. The potential energy acquired in driving to the top of a mountain is the same whether the road goes straight up or zigzags in gradual slopes. Why then do most mountain roads wind up gradually rather than rising straight up with a steep slope?

3. A light truck and a heavy truck are traveling the same speed. It is easier for the light truck to stop. Explain why.


4. A light truck and a heavy truck are moving with the same momentum. Which requires the most work to stop? Explain.


5. When a rifle with a long barrel is fired, the force of expanding gases acts on the bullet for a longer distance. What effect does this have on the velocity of the emerging bullet?

2007-11-29 09:42:28 · 7 answers · asked by crazymongoose129 2

A quarterback throws a football toward a re-ceiver with an initial speed of 17 m=s, at an
angle of 37 above the horizontal. At that
instant, the receiver is 17 m from the quarter-
back.
The acceleration of gravity is 9:8 m=s2 :
With what constant speed should the receiver run in order to catch the football at the
level at which it was thrown? Answer in units
of m=s.

2007-11-29 09:35:08 · 1 answers · asked by Jarod S 2

A ball is thrown straight upward and returns
to the thrower's hand after 2 s in the air. A
second ball is thrown at an angle of 37 with
the horizontal.
The acceleration of gravity is 9:8 m=s2 :
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.

2007-11-29 09:34:22 · 1 answers · asked by Jarod S 2

One of them, of mass 70.0 kg, is moving to the right at 2.00 m/s, while the other, of mass 75.0 kg, is moving to the left at 2.80 m/s.
What are the magnitude of the velocity of these skaters just after they collide?

2007-11-29 09:32:44 · 1 answers · asked by coolredturtle1555 2

1) a runner moving at his speed of 4.5 m/s rounds a curved track with a 64 m radius. what is the runner's centripetal acceleration?
a. 0.07 m/s^2
b. 0.316 m/s^2
c. 288 m/s^2
d. 1296 m/s^2

2) a 58.0 kg skater with a velocity of 16.0 m/s comes into a curve of 24.0 m radius. how much friction must be exerted between the skates and the ice to negotiate the curve?
a. 2088 N
b. 38.7 N
c. 87 N
d. 618.7 N

2007-11-29 09:26:32 · 2 answers · asked by Anonymous

example: a=v2-v1
---------
delta t

2007-11-29 09:23:23 · 1 answers · asked by Anonymous

2007-11-29 09:06:10 · 4 answers · asked by LaurenD 3

(A) The field is uniform.
(B) The field increases in strength as the
distance from the wire increases.
(C) The field lines are directed parallel to the
wire, but opposite to the direction of the
current.
(D) The field lines are directed radially
outward from the wire.
(E) The field lines form circles about
the wire.

2007-11-29 08:57:50 · 3 answers · asked by Jacob L 1

Three identical pendulum clocks have pendulums of equal length L = 25cm.
Two clcoks A and B are located at two stations connected by straigh railroad track, at distance
D = speed of light x 1/2 hour, and are always syncronized (in motionless frame).

The third clock C is aboard a train moving at constant speed c/2. When the train is passing station A, engineer syncronizes clock C to clock A.

What is the differece between clocks B and C, when the train passes station B 1 hour later?

2007-11-29 08:42:03 · 3 answers · asked by Alexander 6

2007-11-29 08:40:44 · 1 answers · asked by Anonymous

a hill is 109.2 m long and makes an angle of 12.99 degrees with the horizontal. as a 54.5 kg jogger runs up the hill, how much work does gravity do on the jogger?

2007-11-29 08:40:41 · 1 answers · asked by Big K 2

Question: Galileo discovered the four major moons of the planet Jupiter in 1610. The nearest one, Io, has a period of 1.7699 days and is 5.578 Jovian radii (Radius of Jupiter) from the center of the planet. Use this data (not from your book's table of planetary information) to calculate the density of Jupiter.

Okay, I've discovered that the Period in seconds is 152919.36 seconds.

Here are some relevant equations:
Density= Mass/volume
Volume= (4/3)*pi*r^3
Period^2=((4*pi^2)/(G(Mass of Jupiter)))*r^m

I know I need to figure out what the Mass of Jupiter is and the radius of Jupiter too. In addition, I need to then find the mass and volume in order to get the density.

Please help me if possible, any information is greatly appreciated!

2007-11-29 08:31:16 · 2 answers · asked by Anon. 2

1) A person weighs 612 N. If this person sits in the middle of a hammock that is 3.0 m long and it sags 1.0 m below the points of support, what force would be exerted by the two hammock ropes.
a. .005 N
b. 204 N
c. 459 N
d. 918 N

2) a stone is thrown horizontally at 10 m/s from the top of a cliff 50 m high. how far from the base of the cliff will it land?
a. 3.4 m
b. 10.2 m
c. 34 m
d. 102 m

3) a soccer player kicks a ball in to the air at an anle of 32 degrees above the horizontal. the initial velocity of the ball is +26.0 m/s. how long is the soccer ball in the air?
a. 0.11 s
b. 1.4 s
c. 2.6 s
d. 2.8 s

2007-11-29 08:28:13 · 3 answers · asked by Anonymous

2007-11-29 08:14:39 · 1 answers · asked by Anonymous

when given a certain mass hanged by lets say two threads....and lets say that your given that each thread can sustain a maximum tension of 25 N (one of the threads is always horizontal while the other is at an angle to the vertical axis).....how can u predict which one will break first if the other is given the maximum 25 N???

2007-11-29 08:07:23 · 1 answers · asked by IEE6000 1

the table. what is the acceleration of the mass along the table?

2007-11-29 07:49:10 · 3 answers · asked by Anonymous

why is it that the term equal force is used if for example a cup is places on a table

the upward force on the table is said to be equal with the gravitational force of the cup.

now if you put a 1kg and a 10kg cup on a table how can the forces be the same to keep the both cups still... if the table is pushing up with the equal force on the 10kg cup, why doesnt the 1kg cup go flying into the air?

2007-11-29 07:48:45 · 4 answers · asked by PistolPete 2

a. no force
b. equal force
c. less force
d. more force

2007-11-29 07:39:28 · 18 answers · asked by Anonymous

How do the humans travel from planet to planet. They must
be traveling faster than the speed of light because some of the planets are 19 light years away and yet the travel time is a month. What propulsion system do they use? If it is faster than the speed of light, then how do they reconcile the time dilation which Einstein's theory of relativity describes? The three Legend books from Dune happen at a time before the ability to fold space so I'm just wondering how they are able to travel so fast (and without the use of computers!).

2007-11-29 07:07:59 · 2 answers · asked by ungoliant2 2

Ok- I always see in these prison related scenes from movies and tv about inmates putting ground glass in food, or being afraid of eating ground glass.

What actually happens when you swallow ground glass? I mean, is it just painful? or is it something that would kill you? Or is this just a myth?

2007-11-29 07:07:22 · 11 answers · asked by nikkilee911 3

2007-11-29 06:52:04 · 8 answers · asked by trer 3

A 17.8 kg person climbs up a uniform 85.1 N ladder. The upper and lower ends of the ladder rest on frictionless surfaces. The bottom of the ladder is fastened to the wall by a horizontal rope that can support a maximum tension of 87.5 N. The angle between the horizontal and the ladder is 56 degrees. The acc. of gravity of 9.8 m/s^2
http://i217.photobucket.com/albums/cc115/twitchdatweek/Hw14squestion3image.jpg
a. Find the tension in the rope when the person is one-third of the way up the ladder; i.e., (10.2m/3 = 3.4 m). Answer in units of N.
b. Find the maximum distance Dmax the person can climb up the ladder before the rope breaks. Answer in units of m.

2007-11-29 05:56:52 · 2 answers · asked by Anonymous

I am not talking about fluoroscent one which produces light equavalent to 50 W incandescent bulb..
Suppose we have a 50 w CFL and 50W Incandescent bulb,would they contribute equally to the electricity bill?

2007-11-29 05:27:02 · 5 answers · asked by Ali 5

A woman living on the equator weighs herself and finds that her apparent mass to be 50 kg. A correction in her mass should be made for the Earth's rotation (centripetal force). What should be her correct mass, assuming that the Earth is a perfect sphere of radius 6.37 x 10^6 meters.

2007-11-29 05:16:16 · 2 answers · asked by labelapark 6

A bicycle starts from rest and travels 1000 feet. Given wheels of diameter 26 inches and no slipping, calculate the final angular position of a spoke on the bicycle wheel that starts at a 30 degree position. Assume counterclockwise rotation.

2007-11-29 05:15:11 · 3 answers · asked by labelapark 6

A frictionless block of mass 2.25 kg is attached to an ideal spring with force constant 290 N/m . At t=0 the spring is neither stretched nor compressed and the block is moving in the negative direction at a speed of 11.0 m/s.
a) Find the amplitude.
b) Find the phase angle. (In rad)

2007-11-29 05:09:31 · 2 answers · asked by Natiphy2007 1

2007-11-29 05:09:00 · 3 answers · asked by brittany a 1

Show that it will roll without any sliding when its speed is reduced to 5/7 v-initial. The transition from pure sliding to pure rolling is
gradual so both sliding and rolling take place during this interval.

Any help would be greatly appreciated.

2007-11-29 04:25:49 · 3 answers · asked by Anonymous