Recent Homework Questions About Physics
A small toy airplane is flying in the xy-plane parallel to the ground. In the time interval t=0 to t=10.0 s, its velocity as a function of time is given by
Saturday, September 27, 2014 at 10:46pm
Student wants to jump from their 3rd floor apartment window to the swimming pool below. The base of the apartment is 8.00 meters from the pools edge. If the window is 20.0 meters high, how fast does the student have to be running horizontally to make sure they make it to...
Saturday, September 27, 2014 at 10:40pm
The roadway bridge over a canal is in the form of an arc of circle of radius what is the maximum car can cross the bridge with the ground at the highest point
Saturday, September 27, 2014 at 10:29pm
An airplane is 50,000 m above an observer and 2.1 km to the west of them and 1.5 km to the north of you. Determine the angle to the plane in the x y axis and the total distance to the plane from you. Choose the x-axis east, y axis north, and z axis up.
Saturday, September 27, 2014 at 10:25pm
It takes the elevator in a skyscraper 4.5s to reach its cruising speed of 11m/s . A 70kg passenger gets aboard on the ground floor. What is the passenger's weight before the elevator starts moving? What is the passenger's weight while the elevator is speeding up?
Saturday, September 27, 2014 at 9:53pm
A satellite is in a circular orbit around an unknown planet. The satellite has a speed of 1.75 104 m/s, and the radius of the orbit is 5.15 106 m. A second satellite also has a circular orbit around this same planet. The orbit of this second satellite has a radius of 8.75 106 ...
Saturday, September 27, 2014 at 8:52pm
An electron in an atom has a speed of 2.2 × 10^6 m/s and orbits the nucleus at a distance of 5 × 10^-11m.a)What is its centripetal acceleration? b)A neutron star of radius 17 km is found to rotate at 5 revolutions per second. What is the centripetal acceleration of...
Saturday, September 27, 2014 at 7:44pm
In a TV set, an electron beam moves with horizontal velocity of 2.5 × 107 m/s across the cathode ray tube and strikes the screen, 44 cm away. The acceleration of gravity is 9.8 m/s2 . How far does the electron beam fall while traversing this distance? Answer in units of m
Saturday, September 27, 2014 at 7:00pm
A police car is traveling at a velocity of 20.0 m/s due north, when a car zooms by at a constant velocity of 44.0 m/s due north. After a reaction time 0.700 s the policeman begins to pursue the speeder with an acceleration of 6.00 m/s^2. Including the reaction time, how long ...
Saturday, September 27, 2014 at 6:34pm
A basketball player throws the ball at a 53degree angle above the horizontal to a hoop which is located a horizontal distance L = 2.4 m from the point of release and at a height h = 0.9 m above it.What is the required speed if the basketball is to reach the hoop?
Saturday, September 27, 2014 at 6:22pm
A ball is thrown at 14 m/s at 57° above the horizontal. Someone located 30 m away along the line3 of the path starts to run just as the ball is thrown. How fast, and in which direction, must the catcher run to catch the ball at the level from which it was thrown?
Saturday, September 27, 2014 at 5:00pm
A block of mass m = 3.60 kg is pushed a distance d = 2.60 m along a frictionless, horizontal table by a constant applied force of magnitude F = 11.0 N directed at an angle è = 28.0° below the horizontal as shown in the figure below.
Saturday, September 27, 2014 at 4:03pm
The barrel of a rifle has a length of 0.97m. A bullet leaves the muzzle of a rifle with a speed of 601m/s. What is the acceleration of the bullet while in the barrel?
Saturday, September 27, 2014 at 3:34pm
A spacecraft is in orbit close to the moon's surface. The centripetal acceleration is 1.6 m/s^2. If the radius of the moon is about 1.7 x 10^6 m, determine: a)the orbital speed b)the period of the orbit
Saturday, September 27, 2014 at 3:27pm
A pot with a flower falls out of a window box in a tall apartment building. It passes the top of a particular window with a velocity of -1.7 m/s. It passes the bottom of this window 0.2800 s later? How tall is the window (watch sign)?
Saturday, September 27, 2014 at 3:21pm
A ball falls 5.00 m to the ground. It remains in contact with the ground for 0.027 s and then rebounds to a maximum height of 1.61 m. What acceleration did the ball experience while it was in contact with the ground?
Saturday, September 27, 2014 at 3:19pm
Consider two toy cars. Car A starts from rest and speeds up with constant acceleration for a time delta t until it reached a speed of v and then continues to travel at this speed. At the moment car A reaches its maximum speed, car B, starting at rest from the same point that ...
Saturday, September 27, 2014 at 3:10pm
A geosynchronous satellite is one that appears to be fixed in the sky, a condition useful for telecommunications. If such a satellite orbits the earth at an altitude of 33000 km above the earth's surface, what is its centripetal acceleration? The radius of the Earth is ...
Saturday, September 27, 2014 at 1:19pm
A basketball is thrown at 45° to the horizontal. The hoop is located 4.4 m away horizontally at a height of 1.1 m above the point of release. What is the required initial speed?
Saturday, September 27, 2014 at 1:18pm
A state trooper chases a speeder along a straight road; both vehicles move at 160 km/h. The siren on the trooper's vehicle produces sound at frequency of 500 Hz. What is the Doppler shift in the frequency heard by the speeder?
Saturday, September 27, 2014 at 12:34pm
An ambulance with a siren emitting a whine at 1600 Hz overtaken and passes a cyclist pedaling a bike at 2.44 m/s. After being passed, the cyclist hears a frequency of 1590 Hz. How fast is the ambulance moving?
Saturday, September 27, 2014 at 12:25pm
An acoustic burglar alarm consists of a source emitting waves of frequency 28.0 kHz. What is the beat frequency between the source waves and the waves reflected from an intruder walking at an average speed of 0.095 m/s directly away from the alarm?
Saturday, September 27, 2014 at 12:16pm
. A 90cm uniform lever has a load of 30N suspended at 15cm from one of its ends. If the fulcrum is at the centre of gravity, calculate the force that must be applied at its other end to keep it horizontal
Saturday, September 27, 2014 at 12:00pm
A satellite of mass 205 kg is launched from a site on Earth's equator into an orbit at 200 km above the surface of Earth. (a) Assuming a circular orbit, what is the orbital period of this satellite? s (b) What is the satellite's speed in its orbit? m/s (c) What is the ...
Saturday, September 27, 2014 at 11:48am
A car travelling at 60 km/h hits a bridge abutment. A passenger in the car moves forward a distance of 67 cm (with respect to the road) while being brought to rest by an inflated air bag. What force (assumed constant) acts on the passenger¡¦s upper torso, which ...
Saturday, September 27, 2014 at 11:26am
The mass of a robot is 6930 kg. This robot weighs 2520 N more on planet A than it does on planet B. Both planets have the same radius of 3.01 × 106 m. What is the difference MA - MB in the masses of these planets?
Saturday, September 27, 2014 at 3:35am
A rocket moves upward, starting from rest with an acceleration of 25.0 m/s2 for 3.77 s. It runs out of fuel at the end of the 3.77 s but does not stop. How high does it rise above the ground I`ve been sick last week, not quite sure where to even start can you give me a formula...
Friday, September 26, 2014 at 11:55pm
A ball is thrown at 15.5 m/s at 42° above the horizontal. Someone located 30 m away along the line3 of the path starts to run just as the ball is thrown. How fast, and in which direction, must the catcher run to catch the ball at the level from which it was thrown?
Friday, September 26, 2014 at 10:53pm
A hockey puck slides with an initial speed of 52.3 m/s on a large frozen lake. If the coefficient of kinetic friction between the puck and the ice is 0.02, what is the speed of the puck after 11.8 s?
Friday, September 26, 2014 at 9:30pm
Your new designer chair has an S-shaped tubular metal frame that behaves just like a spring with the spring constant 13500 N/m. When your friend, who weighs 910 N, sits on the chair, how far does it bend?
Friday, September 26, 2014 at 4:58pm
A bullet is fired vertically upward from a gun and reaches a height of 7000 ft. Find its initial velocity. How long does it take to reach its maximum height? How long is it in flight?
Friday, September 26, 2014 at 4:56pm
A rock is dropped from a bridge to the water below. It takes 2.40 s for the rock to hit the water. Find the speed (in m/s) of the rock as it hits the water. How high (in metres) is the bridge above the water?
Friday, September 26, 2014 at 4:33pm
A skateboarder, with an initial speed of 2.4m/s , rolls virtually friction free down a straight incline of length 19m in 3.3 s.At what angle θ is the incline oriented above the horizontal?
Friday, September 26, 2014 at 3:57pm
A student standing on the ground throws a ball straight up. The ball leaves the student's hand with a speed of 19.0m/s when the hand is 1.50m above the ground. How long is the ball in the air before it hits the ground? (The student moves her hand out of the way.)
Friday, September 26, 2014 at 2:11pm
Two rockets are flying in the same direction and are side by side at the instant their retrorockets fire. Rocket A has an initial velocity of +4800 m/s, while rocket B has an initial velocity of +9000 m/s. After a time t both rockets are again side by side, the displacement ...
Friday, September 26, 2014 at 1:05pm
From the top of a cliff, a person uses a slingshot to fire a pebble straight downward, which is the negative direction. The initial speed of the pebble is 7.56 m/s. (a) What is the acceleration (magnitude and direction) of the pebble during the downward motion? (b) After 0.950...
Friday, September 26, 2014 at 1:04pm
A horizontal force of 3,000,000 dynes can keep a 50 kg mass in uniform motion. What is the coefficient of the kinetic friction? At what angle must the plane be tilted to allow the mass to slide?
Friday, September 26, 2014 at 12:01pm
Two horizontal forces, and , are acting on a box, but only is shown in the drawing. can point either to the right or to the left. The box moves only along the x axis. There is no friction between the box and the surface. Suppose that = +5.6 N and the mass of the box is 3.1 kg...
Friday, September 26, 2014 at 11:03am
A baseball is thrown upward with a velocity of 15m/s. How fast is it moving after 2 seconds? I have no Idea how to begin and the formula he gave us isn't even related to the question at all. (V=vi+at)
Friday, September 26, 2014 at 10:39am
an airplane and a helicopter leave an airport in montana at the same time.The aircrafts velocities:v=225mph@20 degree,and v=102mph@49 degree.If these velocities are maintained which craft will cross the borderinto canada first? or do they arrive at the same time. Try the ...
Friday, September 26, 2014 at 3:28am
a weather station releases a weather balloon.The balloon's buoyancy accelerates it upward at 15m/s sq.At the same time,a wind accelerates it horizontally to the right at 6.5m/s sq.What is the resulting acceleration
Friday, September 26, 2014 at 2:52am
A robot probe drops a camera off the rim of a 387 m high cliff on Mars, where the free-fall acceleration is 3.7 m/s2 . Find the velocity with which it hits the ground. Answer in units of m/s
Friday, September 26, 2014 at 12:49am
4. A ball is kicked toward a fence from a point 32 meters away. The velocity of the ball as it leaves the kickers foot is 24 m/s at an angle of 37 degrees above the horizontal. The top of the fence is 2.0 meters high. Assuming air resistance to be negligible (1 ...
Thursday, September 25, 2014 at 11:44pm
A duck has a mass of 2.2 kg. As the duck paddles, a force of 0.11 N acts on it in a direction due east. In addition, the current of the water exerts a force of 0.12 N in a direction of 50° south of east. When these forces begin to act, the velocity of the duck is 0.12 m/s ...
Thursday, September 25, 2014 at 11:06pm
When a parachute opens, the air exerts a large drag force on it. This upward force is initially greater than the weight of the sky diver and, thus, slows him down. Suppose the weight of the sky diver is 852 N and the drag force has a magnitude of 1012 N. The mass of the sky ...
Thursday, September 25, 2014 at 10:06pm
Scientists are experimenting with a kind of gun that may eventually be used to fire payloads directly into orbit. In one test, this gun accelerates a 1.9-kg projectile from rest to a speed of 5.1 × 103 m/s. The net force accelerating the projectile is 8.6 × 105 N. ...
Thursday, September 25, 2014 at 9:25pm
A block is given an initial velocity of 9.00 m/s up a frictionless incline of angle θ = 21.0°. How far up the incline does the block slide before coming to rest?
Thursday, September 25, 2014 at 8:35pm
A parachute on a person jumping from a plane opens and changes the speed of the person from 65m/s to 35m/s in a period of 4.2 seconds. What is the acceleration of the person?
Thursday, September 25, 2014 at 8:08pm
A stone is tied to a string (length = 0.700 m) and whirled in a circle at the same constant speed in two different ways. First, the circle is horizontal and the string is nearly parallel to the ground. Next, the circle is vertical. In the vertical case the maximum tension in ...
Thursday, September 25, 2014 at 7:44pm
An ice skater skates 28 m southwest, then 56 m east, and finally 84 m in a direction 50.3 ◦ north of east.Find the magnitude of the displacement required to bring the skater back to her starting point. Answer in units of m
Thursday, September 25, 2014 at 7:09pm
A parachute on a person jumping from a plane opens and changes the speed of the person from 65m/s to 35m/s in a period of 4.2 seconds. What is the acceleration of the person?
Thursday, September 25, 2014 at 7:00pm
A box is given a push so that it slides across the floor. How far will it go, given that the coefficient of kinetic friction is 0.25 and the push imparts an initial speed of 6.0m/s?
Thursday, September 25, 2014 at 6:52pm
A car is safely negotiating an unbanked circular turn at a speed of 18 m/s. The road is dry, and the maximum static frictional force acts on the tires. Suddenly a long wet patch in the road decreases the maximum static frictional force to one-ninth of its dry-road value. If ...
Thursday, September 25, 2014 at 6:49pm
Speedboat A negotiates a curve whose radius is 100 m. Speedboat B negotiates a curve whose radius is 221 m. Each boat experiences the same centripetal acceleration. What is the ratio vA/vB of the speeds of the boats?
Thursday, September 25, 2014 at 6:39pm
Consider two spherical stones with same density (mass per unit volume). The larger stone has radius R = 8.58 cm and the smaller stone has radius r = 3.37 cm. Find the ratio of the terminal speed in air of the larger stone to that of the smaller stone.
Thursday, September 25, 2014 at 6:36pm
Suppose that the swimmer in the figure below has a swimming speed relative to the water of 0.40 m/s, while the speed of the current is 2.2 m/s. If it takes the swimmer 200 s to cross the river, how wide is the river
Thursday, September 25, 2014 at 6:24pm
Air rushing over the wings of high-performance race cars generates unwanted horizontal air resistance but also causes a vertical downforce, which helps the cars hug the track more securely. The coefficient of static friction between the track and the tires of a 650-kg race car...
Thursday, September 25, 2014 at 5:54pm
Traveling at a speed of 16.1 m/s, the driver of an automobile suddenly locks the wheels by slamming on the brakes. The coefficient of kinetic friction between the tires and the road is 0.650. What is the speed of the automobile after 1.20 s have elapsed? Ignore the effects of ...
Thursday, September 25, 2014 at 5:54pm
a trolley of mass 40kg us pushed up a hill of height 10m at an angle of 20 degree. calculate the force required to reach this height. how do i complete this question?
Thursday, September 25, 2014 at 4:56pm
A hanging block of mass X is pressed with a force F at angle theta to the vertical against a frictionless wall and is connected to another hanging block of mass Y by a pulley system. What is the expression for the acceleration of Y?
Thursday, September 25, 2014 at 2:36pm
Physics help please
A gamma ray with 700KeV energy is Compton-Scattered from an electron. Find the energy of the photon scattered at 110 degrees, the energy of the scattered electron, and the recoil angle of the electron. i found the photon energy using compton scatter equation at 110 degrees, ...
Thursday, September 25, 2014 at 10:23am
I believe this is a projectile motion problem with the angle = 0 degrees. A ball is thrown horizontally from the roof of a building 7.5 m tall and lands 9.5 m from the base. What was the ball's initial speed? How would I start off this problem? Or set it up throughout?
Thursday, September 25, 2014 at 1:23am
A grocery sack can withstand a maximum of 230 N before it rips. will a bag holding 15 kg of groceries that is lifted from the checkout counter at an acceleration of 7.0 m/s^2 hold? this question has to do with force. thanks..
Thursday, September 25, 2014 at 1:02am
Your friend is an environmentalist who is living in a tree for the summer. You are helping provide her with food, and you do so by throwing small packages up to her tree house. If her tree house is 27 m above the ground, what is the minimum (initial) speed you must use when ...
Wednesday, September 24, 2014 at 11:01pm
A car is moving with a velocity of 10.1m/s [N] while on a ferry that is moving across a lake. If an observer on a shore measures the velocity of the car to be 29.0m/s [N] how quickly is the ferry moving?
Wednesday, September 24, 2014 at 10:25pm
You drop a water balloon on your friends head from the third-story window of your apartment building, 15.0 m from the ground. What is the water balloons acceleration while it is in the air? How much time does it take for the water balloon to fall? How...
Wednesday, September 24, 2014 at 10:06pm
A basketball player achieves a hang time of 0.75 s in dunking the ball. What vertical height will he attain? The acceleration of gravity is 9.8 m/s2 . Answer in units of m
Wednesday, September 24, 2014 at 10:03pm
A bullet is fired straight up from a gun with a muzzle velocity of 225 m/s. Neglecting air resistance, what will be its displacement after 6.1 s? The acceleration of gravity is 9.8 m/s2 . Answer in units of m
Wednesday, September 24, 2014 at 9:38pm
a child slides down a slide with 26 degrees inclined and at the bottom her speed is 1/4 of what it would have been frictionless. Calculate the coefficient of kinetic fiction between the slide and the child?
Wednesday, September 24, 2014 at 9:06pm
Gravity is pulling downward on a 20.0kg block resting on a 15 degree incline. What is the magnitude of the force component parallel to the surface (hint: how to turn 20.0kg into force)?
Wednesday, September 24, 2014 at 7:41pm
A hot-air balloon is rising upward with a constant speed of 2.35 m/s. When the balloon is 2.50 m above the ground, the balloonist accidentally drops a compass over the side of the balloon. How much time elapses before the compass hits the ground?
Wednesday, September 24, 2014 at 6:29pm
you are in a plane traveling due North at 325 km/hr. The plane encounters a headwind (South) wind of 50 km/hr. What is the resultant velocity of the plane?
Wednesday, September 24, 2014 at 6:23pm
The biggest stuffed animal in the world is a snake 420 m long, constructed by Norwegian children. Suppose the snake is laid out in a park as shown in the figure below, forming two straight sides of a 114° angle, with one side 220 m long. Olaf and Inge run a race they ...
Wednesday, September 24, 2014 at 6:13pm
Algebra Based - Physics Help Please!!!!
a) In 1897, Madeline Boardman won the long-drive contest during the U.S. Women's Amateur Golf Tournament. Her winning drive was 125 m. if the ball was hit off the tee at a 45 degree angle, what did the magnitude of its initial velocity have to be for her to make the ...
Wednesday, September 24, 2014 at 5:51pm
A cat is being chased by a dog. Both are running in a straight line at constant speeds. The cat has a head start of 3.6 m. The dog is running with a speed of 8.9 m/s and catches the cat after 6.9 s. How fast did the cat run?
Wednesday, September 24, 2014 at 5:19pm
You're squeezing a springy rubber ball in your hand. If you push inward on it with a force of 1 N, it dents inward 2 mm. How far must you dent it before it pushes outward with a force of 3 N?
Wednesday, September 24, 2014 at 5:05pm
Physics of Modern Technology
Label as true each of the following processes that are considered destructive to cells of a living organism (like you!). Label as false if they are not considered significantly destructive to cells of a living organism. A slow neutron combines with a Hydrogen nucleus in a ...
Wednesday, September 24, 2014 at 4:59pm
Your new designer chair has an S-shaped tubular metal frame that behaves just like a spring with the spring constant 13000 N/m. When your friend, who weighs 940 N, sits on the chair, how far does it bend?
Wednesday, September 24, 2014 at 4:56pm
Two cylindrical copper wires have the same mass and are at the same temperature. Wire A is twice as long as wire B. The resistance of wire A is related to that of wire B by a) RA = RB/4 b) RA = RB/2 c) RA = RB d) RA = 2RB e) RA = 4RB
Wednesday, September 24, 2014 at 4:34pm