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September 20, 2014

Posts by Elisa


Total # Posts: 147

physics
1. A 10.0 g object moving to the right at 25.0 cm/s makes an elastic head-on collision with a 15.0 g object moving in the opposite direction at 36.0 cm/s. Find the velocity of each object after the collision. 10.0 g object: 15.0g object: 2. A dentist's drill starts from ...
July 7, 2008

physics
A 45.0 kg girl is standing on a 163 kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat, frictionless surface. The girl begins to walk along the plank at a constant velocity of 1.45 m/s relative to the plank. (a) What is her velocity ...
July 7, 2008

physics
Calculate the magnitude of the linear momentum for the following cases. (a) a proton with mass 1.67 10-27 kg, moving with a speed of 4.00 106 m/s (b) a 16.5 g bullet moving with a speed of 270 m/s (c) a 70.5 kg sprinter running with a speed of 12.5 m/s (d) the Earth (mass = 5....
July 7, 2008

physics
1. A centrifuge in a medical laboratory rotates at an angular speed of 3650 rev/min. When switched off, it rotates through 50.0 revolutions before coming to rest. Find the constant angular acceleration of the centrifuge. 2. A ball of mass 0.120 kg is dropped from rest from a ...
July 6, 2008

physics
An archer shoots an arrow toward a 300 g target that is sliding in her direction at a speed of 2.35 m/s on a smooth, slippery surface. The 22.5 g arrow is shot with a speed of 41.0 m/s and passes through the target, which is stopped by the impact. What is the speed of the ...
July 6, 2008

physics
1. A 3.25 kg steel ball strikes a wall with a speed of 10.0 m/s at an angle of 60.0° with the surface. It bounces off with the same speed and angle. If the ball is in contact with the wall for 0.195 s, what is the average force exerted on the ball by the wall? x component...
July 6, 2008

physics
A rotating wheel requires 5.00 s to rotate 30.0 revolutions. Its angular velocity at the end of the 5.00 s interval is 100.0 rad/s. What is the constant angular acceleration of the wheel?
July 6, 2008

physics
An 8.00 g bullet is fired into a 180 g block that is initially at rest at the edge of a table of 1.00 m height. The bullet remains in the block, and after the impact the block lands d = 2.2 m from the bottom of the table. Determine the initial speed of the bullet.
July 6, 2008

physics
A 705 N man stands in the middle of a frozen pond of radius 4.0 m. He is unable to get to the other side because of a lack of friction between his shoes and the ice. To overcome this difficulty, he throws his 1.2 kg physics textbook horizontally toward the north shore at a ...
July 6, 2008

physics
The force shown in the figure below is the net eastward force acting on a ball. The force starts rising at t=0.012 s, falls back to zero at t=0.062 s, and reaches a maximum force of 35 N at the peak. Determine with an error no bigger than 25% (high or low) the magnitude of the...
July 2, 2008

physics
The force sensor measures the force on the sensor due to the bumper, but the cart's momentum change arises from the force on the cart due to the bumper. Which of the following facts are needed to assert that the magnitude of these two forces are nearly equal at all times. ...
July 2, 2008

physics
A bat hits a moving baseball. If the bat delivers a net eastward impulse of 0.7 N-s and the ball starts with an initial horizontal velocity of 3.8 m/s to the west and leaves with a 5.2 m/s velocity to the east, what is the mass of the ball (in grams)?
July 2, 2008

Physics
Find the tension in the two wires that support the 100 N light fixture. Assume θ is 39°. left wire: right wire:
June 9, 2008

Physics
Add the two forces vectorially? meaning?
June 9, 2008

Physics
The force exerted by the wind on the sails of a sailboat is 310 N north. The water exerts a force of 240 N east. If the boat (including its crew) has a mass of 330 kg, what are the magnitude and direction of its acceleration? magnitude in m/s2 direction in ° north of east
June 9, 2008

Physics
it worked now.. thank you.. i forgot to convert!
June 9, 2008

Physics
Hello. I keep repeating the problem and I get a huge number.
June 9, 2008

Physics
A 4.0 g bullet leaves the muzzle of a rifle with a speed of 310 m/s. What force (assumed constant) is exerted on the bullet while it is traveling down the 0.9 m long barrel of the rifle?
June 9, 2008

physics
A 3.6 kg mass hangs at one end of a rope that is attached to a support on a railroad car. When the car accelerates to the right, the rope makes an angle of 1.0° with the vertical. Find the acceleration of the car.
June 9, 2008

Physics
Two blocks are fastened to the ceiling of an elevator as in Figure P4.19. The elevator accelerates upward at 2.00 m/s2. The blocks both have a mass of 14.0 kg. Find the tension in each rope. top rope: bottom rope:
June 9, 2008

Physics
The figure shows m1 going straight down and m2 on an incline.
June 9, 2008

Physics
Two packing crates of masses m1 = 10.0 kg and m2 = 3.50 kg are connected by a light string that passes over a frictionless pulley as in Figure P4.26. The 3.50 kg crate lies on a smooth incline of angle 37.0°. Find the acceleration of the 3.50 kg crate. up the incline: Find...
June 9, 2008

physics
An object with mass m1 = 5.00 kg, rests on a frictionless horizontal table and is connected to a cable that passes over a pulley and is then fastened to a hanging object with mass m2 = 9.0 kg, as shown in Figure P4.30. Find the acceleration of each object and the tension in ...
June 9, 2008

physics
A woman at an airport is towing her 27.0 kg suitcase at constant speed by pulling on the strap at an angle θ above the horizontal. She pulls on the strap with a 32.0 N force, and the friction force on the suitcase is 11.0 N. (a) What angle does the strap make with the ...
June 8, 2008

physics
Objects of masses m1 = 4.00 kg and m2 = 9.00 kg are connected by a light string that passes over a frictionless pulley as in Figure P4.48. The object m1 is held at rest on the floor, and m2 rests on a fixed incline of θ = 42.0°. The objects are released from rest, and...
June 8, 2008

Physics
So in which one would the graph of position vs time be a parabola? If the object moves along a straight line, then wouldn't the position graph just be an increasing line with with positive slope?
June 4, 2008

Physics
There is a parabolic position vs time graph. Which of these is true: The object moves 1. in a parabolic trajectory. 2. along a straight line. 3. along an arc of a circle wouldn't 1 and 3 produce the same/similar position graph?
June 4, 2008

physics
A quarterback throws a football toward a receiver with an initial speed of 21 m/s at an angle of 30° above the horizontal. At that instant, the receiver is 12 m from the quarterback. In what direction and with what constant speed should the receiver run in order to catch ...
June 2, 2008

physics
okay: I got the vector from A to B and then the vector from B to C to get the distance from A to C. I got 200.00 from the vector from A to B and then 280.00 from the vector from B to C. I added them, but the answer is incorrect. For A to B: I did 200cos30.5 200sin30.5 Then I ...
June 2, 2008

physics
An airplane flies 200 km due west from city A to city B and then 280 km in the direction of 30.5° north of west from city B to city C. (a) In straight-line distance, how far is city C from city A? (b) Relative to city A, in what direction is city C? The answer is: 17.8 ...
June 2, 2008

physics
that is the speed I originally got, but it is supposedly wrong.
June 2, 2008

physics
A quarterback throws a football toward a receiver with an initial speed of 21 m/s at an angle of 30° above the horizontal. At that instant, the receiver is 12 m from the quarterback. In what direction and with what constant speed should the receiver run in order to catch ...
June 2, 2008

physics
thank you.
June 2, 2008

physics
A jet airliner moving initially at 300 mi/h due east enters a region where the wind is blowing at 100 mi/h in a direction 26.0° north of east. What is the new velocity of the aircraft relative to the ground? in m/h at degrees North of east.
June 2, 2008

physics
I get 35.9m for a, which checks out but I keep getting 2.47s for b, which is supposedly wrong.
June 1, 2008

physics
A car is parked on a cliff overlooking the ocean on an incline that makes an angle of 20.0° below the horizontal. The negligent driver leaves the car in neutral, and the emergency brakes are defective. The car rolls from rest down the incline with a constant acceleration ...
June 1, 2008

physics
An airplane flies 200 km due west from city A to city B and then 280 km in the direction of 30.5° north of west from city B to city C. (a) In straight-line distance, how far is city C from city A? in km? (b) Relative to city A, in what direction is city C? how many° ...
June 1, 2008

Physics
A quarterback throws a football toward a receiver with an initial speed of 21 m/s at an angle of 30° above the horizontal. At that instant, the receiver is 12 m from the quarterback. In what direction and with what constant speed should the receiver run in order to catch ...
June 1, 2008

Physics
A boat moves through the water of a river at 5 m/s relative to the water, regardless of the boat's direction. If the water in the river is flowing at 1.3 m/s, how long does it take the boat to make a round trip consisting of a 215 m displacement downstream followed by a ...
June 1, 2008

Physics
sorry i posted this twice!
June 1, 2008

Physics
A boat moves through the water of a river at 5 m/s relative to the water, regardless of the boat's direction. If the water in the river is flowing at 1.3 m/s, how long does it take the boat to make a round trip consisting of a 215 m displacement downstream followed by a ...
June 1, 2008

Physics
I get 2.64 feet.
June 1, 2008

Physics
One of the fastest recorded pitches in major-league baseball, thrown by Billy Wagner in 2003, was clocked at 101.0 mi/h . If a pitch were thrown horizontally with this velocity, how far would the ball fall vertically by the time it reached home plate, 60.5 ft away? I tried to ...
June 1, 2008

Physics
Thanks!
June 1, 2008

Physics
A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 15.0 m/s. The cliff is h = 66.0 m above a flat horizontal beach. How long after being released does the stone strike the beach below the cliff? I got 3.67 s. With what speed ...
June 1, 2008

math
A 5% alcohol solution is mixed with 15% alcohol solution to make a 25mlof a 9% solution. How much of each alcohol solution is used?
October 29, 2007

chemistry question check
consider the following chemical reaction: 2 H20 ---> 2H2 + O2 How many moles of H20 are required to form 1.8 L of O2 at a temperature of 315 K and a pressure of 0.957 atm? I got 0.066 moles. Correct? Nope. Do you have some reasoning that you followed you want to have ...
March 29, 2007

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