Physics - November 2007

An object of a given weight is pulled at a constant velocity with a given force by a rope that makes a given angle of with the horizontal. Calculate (a) the
horizontal component of the force exerted by the rope and (b) the force of friction between the sled and the ground.

2007-11-20 12:26:29 · 1 answers · asked by Anonymous

I'm on Mars.

2007-11-20 12:18:04 · 7 answers · asked by Anonymous

The world population is expanding at a very fast rate and is not expected to even out until the next century. Considering the world is getting heavier every second, it is conceivable that it will eventually surpass the mass of the earth.
Will the population of the world become the same as the earth? What might happen then?

2007-11-20 11:50:58 · 12 answers · asked by Anonymous

2007-11-20 11:48:02 · 2 answers · asked by Rachel P 1

What's the formula for newton's third law?

2007-11-20 11:43:22 · 2 answers · asked by Lala! 1

2007-11-20 11:40:03 · 7 answers · asked by kinghout28 2

You've seen them in games, television shows and movies, gigantic "battleships" or spaceships if you will. Is it even remotely possible? Take the space variable out of it and given that we have "thrusters" to move it and the fact of it's massive size, won't it take years just to complete one? And the resources, do we even have enough? What about the required amount of people just to keep it running? I'm sure there are other problems that prevent it from becoming possible but I can't think of them right now, what do you think, possible or not?

2007-11-20 11:29:05 · 1 answers · asked by troyk 1

Hopping into your Porsche, you floor it and accelerate at 9.1 m/s^2 without spinning the tires. Determine the minimum coefficient of static friction between the tires and the road needed to make this possible.

Please show/explain all work clearly please.

2007-11-20 10:57:44 · 1 answers · asked by Anonymous

A box is pulled at an angle of 37 degrees above the horizontal with a force of 50 N. The mass of the box is 40 kg and the coefficient of kinetic friction is 0.4. Calculate the quantities for the blanks below.

weight ________
F(subscript x) __________
Normal force (W-Fsubscript y) _________
F (force of friction) __________
F(subscript net) ____________
Acceleration __________

Please show/explain all work clearly please.

2007-11-20 10:55:21 · 1 answers · asked by nirmal 1

1: The vertical and horizontal motions of a projectile are:
The same
Inversely proportional to one another
Directly proportional to one another
Independent of one another


2: The range of a projectile depends upon the acceleration due to gravity and upon both components of the initial:
Force
Position
Velocity
Acceleration


3: The angle that results in the maximum range of a projectile is:
180 deg.
30 deg.
45 deg.
60 deg


4: An arrow is shot at 30.0 degrees above the horizontal. Its initial velocity is 49 m/s and it hits the target. What is the maximum height the arrow will attain?
49 m
25 m
75 m
30 m


5: In question # 4, if the target is at the same height from which the arrow was shot, how far away is the target?
1.1 x 104m
2.1 x 104m
1.1 x 102m
2.1 x 102m


6: A dart player throws a dart horizontally at a speed of 12.4 m/s. The dart hits the board 0.32m below the height from which it was thrown. How much time does it take for the dart to hit the board?
2.6 s
3.2 s
4.5 s
0.8 s


7: A basketball player tries to make a half court jump shot, releasing the ball at the height of the basket. Assuming that the ball is launched at 51 degrees, 14.0m from the basket, what speed must the player give the ball?
140 m/s
9.4 m/s
11.8 m/s
13.3 m/s


8: The range of a projectile launched at an angle is the same for which two angles?
15 degrees and 75 degrees
45 degrees and 30 degrees
45 degrees and 60 degrees
Answers b and c only


9: A ball is thrown at an angle of 66.0 degrees above the horizontal with an initial velocity of 4.47 m/s. What is the maximum height the ball attains?
1.532 m
1.698 m
0.849 m
2.55 m


10: In question # 9, what is the range of the ball thrown. (hint: use x = R; so x = vx0t)
1.51 m
3.02 m
1.36 m
1.70 m


11: In which of the following examples is a net force of zero acting on the object in question? I. A car drives around a circular racetrack at a constant speed. II. A person pushes on a door to hold it shut. III. A ball, rolling across a grassy field, comes to a stop.
I only
II only
III only
I and II


12: In figure 1 above a block is suspended from two ropes, so that it hangs motionless in the air. If the magnitude of T2 is 10.0 N, what is the magnitude of T1?
.500 N
0.866 N
10.0 N
17.3 N


13: A 50 kg crate rests on the floor. The coefficient of static friction is 0.5. The force parallel to the floor needed to move the crates is most nearly:
50 N
125 N
250 N
500 N


14: A person is pushing an object of mass m along the ground with a force F. The coefficient of kinetic friction between the object and the ground is (mu)k. The object is accelerating, but then the person stops pushing and the object slides to a halt. The person then starts pushing again with a force F, but the object doesn't budge. The maximum coefficient of static friction between the object and ground is ms. Which of the following statements is true?
F>(mu)k/(mu)s
(mu)kmgsmg
(mu)smg=F
The scenario described is physically impossible.


15: A 1 kg mass on a frictionless inclined plane is connected by a pulley to a hanging 5.0 kg mass, as in figure 2 above. At what angle will the system be in equilibrium? (in degrees)
-45
-30
30
45


16: A man of mass 80 kg sits in a chair. What it the magnitude of the normal force exerted on the man by the chair?
70.2 N
80 N
89.8 N
784 N


17: A force F acts on object A of mass m1. An identical force acts on object B of mass m2. A experiences acceleration a1 and B experiences acceleration a2. If a2 = 2a1, what is m2 in terms of m1?
1/2 m1
m1
2m1
4m1


18: Which is a vector quantity?
distance
speed
power
force


19: A granite block is being slid at a constant speed across a horizontal concrete floor by a force parallel to the floor. Which pair of quantities could be used to determine the coefficient of friction for the granite on the concrete?
mass and speed of the block
mass and normal force on the block
frictional force and speed of the block
frictional force and normal force on the block


20: After a model rocket reached its maximum height, it then took 5.0 seconds to return to the launch site. Neglecting air resistancce, what is the approximate maximum height reached by the rocket?
49m
98m
120m
250m


21: What term describes how well the results of an experiment agree with the standard value?
Accuracy
Precision
Uncertainty
Reproducibility


22: Which of the following is the largest number?
1.23 E+4
1.23 x 10^4
12300
all of the above


23: The measurement 0.001234 g has how many significant digits?
4
2
3
1


24: According to graphing convention, the values of the dependent variable are plotted
vertically (on the x-axis).
vertically (on the y-axis).
horizontally (on the x-axis).
horizontally (on the y-axis).


25: Which of the following, is a place where you mightfind a physicist working?
high schools
hospitals
Wall Street
all of the above

2007-11-20 10:24:40 · 4 answers · asked by Anonymous

2007-11-20 09:51:20 · 5 answers · asked by Alexander 6

1 - 80g of lead is coated with 30g of mercury. if the densities of lead & mercury are 11.37g/cm^3 and 13.6g/cm^3, calculate the density of the amalgam.

2 - A student mistakenly added 50cm^3 of methylated spirit to 100cm^3 of water. calculate the density of the mixture given density of methylated spirit and that of water to be 0.76g/cm^3 and 1.0g/cm^3

may god bless all who helps me in these questions.....AMEN!

2007-11-20 09:04:26 · 1 answers · asked by Anonymous

and what would happen if it did become discarded?

2007-11-20 08:56:15 · 1 answers · asked by Anonymous

a player kicks a football from the ground level with a velocity of magnitude 27.0 m/s at an angle of 30.0 degrees above the horizontal.

2007-11-20 08:37:40 · 1 answers · asked by lilpinai1788 1

2007-11-20 08:34:55 · 3 answers · asked by RoRoStar 1

I study glass and i want to know properties of fluorescent glass...

2007-11-20 08:11:49 · 3 answers · asked by Sofia C 2

Fill the tanks with the same type of gas. Determine how many miles they travel. Fill the tanks again. Determine the gas consumed by each. Calculate the equivalent amount of energy spent by each car (I need the equivalent amount of energy per gallon of gas). Calculate the energy per mile consumed by each car. I need to describe my procedure, record measurements and calculations. I just don't know where to start. Please help!

2007-11-20 08:00:32 · 1 answers · asked by Anonymous

2007-11-20 07:57:03 · 2 answers · asked by Anonymous

A 57.0 kg person jumps from rest off a 11.0 m high tower straight down into the water. Neglect air resistance during the descent. She comes to rest 3.00 m under the surface of the water. Determine the average force that the water exerts on the diver. This force is nonconservative.

2007-11-20 07:52:47 · 3 answers · asked by Anonymous

An electron and a proton are each placed at
rest in an electric field of 520 N/C. Calculate
the speed of each particle 48.0 ns after
being released.

2007-11-20 07:45:08 · 2 answers · asked by Anonymous

The burner on an electric stove has a power output of 2 kW . A 660 g stainless steel tea kettle is filled with 20 degree C water and placed on the already hot burner. If it takes 2.60 min for the water to reach a boil, what volume of water, in cm^3, was in the kettle? Stainless steel is mostly iron, so you can assume its specific heat is that of iron.

2007-11-20 07:31:49 · 1 answers · asked by Anonymous

Two people start at the same place and walk around a circular lake in opposite directions. One has an angular speed of 1.80E-3 rad/s, while the other has an angular speed of 3.60E-3 rad/s. How long will it be before they meet?

Do I use w = 2(pi)/T?

Thanks!

2007-11-20 07:29:53 · 2 answers · asked by Anonymous

A bullet is show through a musket 600m/s. The musket is .9m long with what acceleration is the bullet being shot?

2007-11-20 07:22:27 · 1 answers · asked by Rachel P 1

What I mean is if ingredients have, say, 50kcal per 100g serving, would the label say 50kcal or 42kcal?

2007-11-20 07:12:18 · 1 answers · asked by Alexander 6

A man attempts to move a stationary object that weighs 152 N. The coefficient of static friction is .35 and the kinetic friction is .27

1. How much force must be applied to get the cabinet moving?

2. If the same force required to start the motion is applied to the cabinet after it starts to move, what is the cabinet's acceleration?

please help me!

2007-11-20 06:43:42 · 2 answers · asked by hotmvper2k3 1

Three charges are at the corners of an
equilateral triangle, measuring 0.5 m on
each side. The charges are:
q1= 2 μC, q2= 7 μC, q3 =-4 μC
1. Calculate the electric field at the position
of the 2 μC due to q2 and q3.
2. Use the field to determine the force on
q1.

2007-11-20 06:41:06 · 1 answers · asked by Anonymous

2007-11-20 06:09:13 · 2 answers · asked by Anonymous

And don't say it's not true coz it is.

2007-11-20 05:52:50 · 9 answers · asked by Anonymous

2007-11-20 05:52:45 · 3 answers · asked by Anonymous

2007-11-20 05:29:43 · 1 answers · asked by Anonymous