Physics - November 2007

The question is:

An apple floating in water displaces 50 cm^3 of water (one cm^3 of water has a mass of 1.0 grams). What is the buoyant force on this apple?

How do I work this one out. I know that d=m/v, but would this formula even apply?

2007-11-19 15:37:03 · 2 answers · asked by platypus 2

A 61 kg skier speeds down a trail, as shown below. The surface is smooth and inclined at an angle of theta = 18 degrees with the horizontal.

a. Draw a free-body diagram for the skier. (Explain how would you draw something like this?)

b. Calculate the normal force on the skier.

c. Assuming that the snow is frictionless, calculate the acceleration of the skier.

2007-11-19 15:19:36 · 1 answers · asked by nirmal 1

Starting from rest, a 5 kg block slides 2.5 m down a rough 30 degree incline in 2 s.
a. What is the work done by the force of gravity
b. What is the mechanical energy lost due to friction
c. What is the work done by the normal force between the block and the incline



2) A 50 kg pole vaulter running at 10 m/s vaults over the bar. If the vaulter's horizontal component of velocity over the bar is 1 m/s and air resistance is disregarded, how high was the jump

2007-11-19 15:12:52 · 3 answers · asked by Doc. Ock 3

what unit is used to measure the mass of an atom?

2007-11-19 15:04:12 · 7 answers · asked by Anonymous

Please?!

2007-11-19 14:54:32 · 1 answers · asked by Ge Y 2

A pitcher throws a curveball that reaches the catcher in 0.49 s. The ball curves because it is spinning at an average angular velocity of 360 rev/min (assumed constant) on its way to the catcher's mitt. What is the angular displacement of the baseball (in radians) as it travels from the pitcher to the catcher?

2007-11-19 14:48:15 · 1 answers · asked by Anonymous

the distance, mass, and initial & final velocities are given!

2007-11-19 14:44:36 · 5 answers · asked by tj.spiffy 1

A hiker, who weighs 1180 N, is strolling through the woods and crosses a small horizontal bridge. The bridge is uniform, weighs 3840 N, and rests on two concrete supports, one at each end. He stops one-fifth of the way along the bridge. What is the magnitude of the force that a concrete support exerts on the bridge at each end?

2007-11-19 14:43:51 · 1 answers · asked by Anonymous

2007-11-19 14:42:27 · 1 answers · asked by Kaley 2

2007-11-19 14:30:46 · 6 answers · asked by *click* 3

How can a Bumble Bee fly if it defies all known scientific laws?

This is one that even graduates of MIT cannot answer!

2007-11-19 14:29:45 · 3 answers · asked by E. Paul S 3

What considerations are required such as
-weight of the vehicle
-direct drive vs pulleys or gears
-anticipated maximum speed
-vehicle shape
-wheels/tyres
-expected terrain
etc etc etc

Is there a mathematical formula that I can use to calculate what motor is required for eg. 2kg or 10 kg or 100kg vehicle to travel at various speeds, and how can I calculate the effect of other factors of the vehicle. How much extra power is required if some form of alternator/generator is added?

2007-11-19 14:23:29 · 1 answers · asked by goodinthecrib 2

ok, a 90kg clock initially at rest on a horizontal floor requires a 650 N horizontal force to set it in motion. After the clock is in motion, a horizontal force of 560 N keeps it moving with a constant speed. find mu s and mu k between the clock and the floor.

Any help at all is appreciated. thanks!

2007-11-19 14:15:24 · 3 answers · asked by mafblue98 1

Two straight parallel wires carry current equal in mag but opposite in direction. What's the net magnetic field due to these two wires at point a, midway between the wires.

a. directly to the right
b. directly to the left
c. directly upward.


Diagram:
http://session.masteringphysics.com/problemAsset/1019994/2/20-6.jpg

2007-11-19 14:03:20 · 2 answers · asked by ~Brigit~ 2

A car with a mass of 1.50 x 10^3 kg starts from rest and accelerates to a speed of 18 m/s in 12 s. Assume that the force of resistance remains constant at 400 N during this time. What is the average power developed by the car's engine??



How long does it take a 19 kW steam engine to do 6.8 x 10^7 J of work??

2007-11-19 13:49:03 · 2 answers · asked by Doc. Ock 3

Explain by using infomation regarding the definition of a load and the movement of electrons

2007-11-19 13:30:47 · 3 answers · asked by lolipop18 3

If you were able to drive along the equator in the opposite direction at the same speed that the Earth is turning, at high noon, would you ever see night-time?

2007-11-19 13:19:29 · 3 answers · asked by Julie C 2

2007-11-19 12:54:50 · 1 answers · asked by Eric D 1

thnx for ur help

2007-11-19 12:47:52 · 1 answers · asked by lachar1991 1

A 215-N box is placed on an inclined plane that makes a 35.0 degree angle with the horizontal.

2007-11-19 12:40:41 · 2 answers · asked by georgie0515 1

Near the end of the track, there is a hemishperical hill (x) inches high. The ball rolls up the hill, down the other side, and crosses a finish line with a total travel time of t(1).

The experiment is repeated with all variables identical, except that the hemishperical hill is changed to a mirror image hemispherical valley with depth (x). The ball rolls out onto the flat section of track, through the depression, and crosses a finish line with a total travel time of t(2).

Neglect friction. Assume that the diameter of the ball is very small compared to the diameter of the hemispherical hill and valley (they travel the same total distance). Assume that the ball never leaves the track.

Which ball finishes first?

2007-11-19 12:14:33 · 2 answers · asked by J G 1

Ok out of all of the questions I'm working on I have figured out all but these three they are giving me some trouble.



Question 1: Two identical brass balls mounted on wooden posts initially have different types of charge, +3uC and the other +15uC. The ball are allowed t touch and then are seperated again. What is the final charge on each ball?


Question 2: Two positive charges, each of magnitude 4 X 10 to the power of -6 C, are located a distance of 10cm from each other. What is the magnitude of the force exerted on each charge?


Question 3:An electron and a proton have charges of an equal magnitude but opposite sign of 1.6 x 10 to the power of -19 C. If the electron and a proton in a hydrogen atom are seperated by a distance of 5 x 10 to the power of -11 m, what are the magnitude and direction of the electrostatic force exerted on the electron by the protron?

2007-11-19 12:00:39 · 1 answers · asked by cassandra 2

like dalton's theory and Bohrs theory and stuff like that

2007-11-19 11:59:19 · 1 answers · asked by Me 2

A bicyclist of mass 70.0 kg puts all his mass on each downward-moving pedal as he pedals up a steep road. Take the diameter of the circle in which the pedals rotate to be 0.40 m, and determine the magnitude of the maximum torque he exerts about the rotation axis of the pedals.

I need some help with this torque problem. What equations do I need to use? Thanks!

2007-11-19 11:51:30 · 2 answers · asked by nglennie_06 1

A phone cord is 4.85 m long. The cord has a mass of 0.200 kg. A transverse wave pulse is produced by plucking one end of the taut cord. The pulse makes four trips down and back along the cord in 0.780 s. What is the tension in the cord?

2007-11-19 11:41:58 · 1 answers · asked by Anna H 2

Is a car tire that is partly deflated more dence, less dense, or of the same density as a totally inflated tire? Why?

2007-11-19 11:40:02 · 2 answers · asked by Anonymous

A softball of mass 0.220 kg that is moving with a speed of 8.5 m/s (in the positive direction) collides head-on and elastically with another ball initially at rest. Afterward the incoming softball bounces backward with a speed of 3.7 m/s.

(a) Calculate the velocity of the target ball after the collision.
(b) Calculate the mass of the target ball.

2007-11-19 11:38:54 · 1 answers · asked by ____ 3

at the same time, a stationary trumpeter played the same note. Ballot heard 3.0 beats per second. How fast was the train moving toward him?
- please include how you do it... need help with homework

2007-11-19 11:34:32 · 1 answers · asked by Anonymous

A horizontal 795 N merry-go-round is a solid disk of radius 1.40m, started from rest by a constant horizontal force of 50.3 N applied tangentially to the edge of the disk. Find the kinetic energy of the disk after 2.96s.

soooo stuck i think you need to find torque but i really have no idea

2007-11-19 11:29:03 · 2 answers · asked by Anonymous

When an athlete holds a barbell overhead, the
reaction force is the weight of the barbell on
his hand.
How does this force vary for the case where
the barbell is decelerated upward?
1. The force exerted by the athlete is equal
to the weight of the barbell.
2. The force exerted by the athlete is smaller
than the weight of the barbell.
3. It depends on the will of the athlete.
4. The force exerted by the athlete is greater
than the weight of the barbell

2007-11-19 11:16:59 · 1 answers · asked by Sarah B 1