A car is stopped at a traffic light. It then travels along a straight road such that its distance from the light is given by , where and (a) Calculate the average velocity of the car for the time interval t = 0 to t = 10.0 s. (b) Calculate the instantaneous velocity of the car at t=0, t = 5.0 s, and t = 10.0 s. (c) How long after starting from rest is the car again at rest?
The diffuser in a jet engine is designed to decrease the kinetic energy of the air entering the engine compressor without any work or heat interactions. Calculate the velocity at the exit of a diffuser when air at 100 kPa and C enters it with a velocity of 350 m/s and the exit state is 200 kPa and
A boat is pulled into a dock by means of a winch 12 feet above the deck of the boat.
(a) The winch pulls in rope at a rate of 4 feet per second. Determine the speed of the boat when there is 13 feet of rope out. What happens to the speed of the boat as it gets closer to the dock?
(b) Suppose the boat is moving at a cons tant rate of 4 feet per second. Determine the speed at which the winch pulls in rope when the re is a tota l of 13 feet of rope out. What happens to the speed at which the winc h pulls in rope as the boat gets closer to the dock ?
A well-insulated rigid tank contains 3 kg of saturated liquid-vapor mixture of water at 200 kPa. Initially, three-quarters of the mass is in the liquid phase. An electric resistance heater placed in the tank is now turned on and kept on until all the liquid in the tank is vaporized. Determine the entropy change of the steam during this process. Answer: 11.1 kJ/K
a. When the displacement of a mass on a spring is A, what fraction of the mechanical energy is kinetic energy and what fraction is potential energy? b. At what displacement, as a fraction of A, is the energy half kinetic and half potential?
3.19 Win the Prize. In a carnival booth, you can win a stuffed giraffe if you toss a quarter into a small dish. The dish is on a shelf above the point where the quarter leaves your hand and is a horizontal distance of 2.1 m from this point (Fig. E3.19). If you toss the coin with a velocity of 6.4 m/s at an angle of 60° above the horizontal, the coin will land in the dish. Ignore air resistance. (a) What is the height of the shelf above the point where the quar ter leaves your hand? (b) What is the vertical component of the velocity of the quarter just before it lands in the dish?
Point charges and are placed 1.0 m apart. What is the force on a third charge placed midway between q1 and q2?
In the figure a worker lifts a weight by pulling down on a rope with a force . The upper pulley is attached to the ceiling by a chain,and the lower pulley is attached to the weight by another chain.The weight is lifted at constant speed. Assume that the rope,pulleys, and chains all have negligible weights.
A) In terms of ,find the tension in the lower chain.
B) In terms of ,find the tension in upper chain.
C) In terms of ,find the magnitude of the force if the weight is lifted at constant speed.
Until he was in his seventies, Henri LaMothe excited audiences by belly-flopping from a height of 13 m into 35 cm. of water. Assuming that he stops just as he reaches the bottom of the water and estimating his mass to be 72 kg, find the magnitudes of the impulse on him from the water.
Flux through a Cube (Eigure 1) A cube has one corner at the origin and the opposite corner at the point (L, L, L). The sides of the cube are parallel to the coordinate planes
A 2.0-kg projectile is fired with initial velocity components m/s and m/s from a point on the earth's surface. Neglect any effects due to air resistance. What is the kinetic energy of the projectile when it reaches the highest point in its trajectory? How much work was done in firing the projectile?
A slab of insulating material of uniform thickness d, lying between to along the x axis, extends infinitely in the y and z directions, as shown in the figure. The slab has a uniform charge density . The electric field is zero in the middle of the slab, at x=0. Which of the following statements is true of the electric field at the surface of one side of the slab?
A helicopter carrying dr. evil takes off with a constant upward acceleration of . Secret agent austin powers jumps on just as the helicopter lifts off the ground. Afterthe two men struggle for 10.0 s, powers shuts off the engineand steps out of the helicopter. Assume that the helicopter is infree fall after its engine is shut off and ignore effects of airresistance.
a) What is the max height above ground reached by the helicopter?
b) Powers deploys a jet pack strapped on his back 7.0s after leaving the helicopter, and then he has a constant downward acceleration with magnitude 2.0 m/s2. how far is powers above the ground when the helicopter crashes into the ground.
A box is sliding with a speed of 4.50 m/s on a horizontal surface when, at point P, it encounters a rough section. On the rough section, the coefficient of friction is not constant but starts at .100 at P and increases linerly with distance past P, reaching a value of .600 at 12.5 m past point P. (a) Use the work energy theorem to find how far this box slides before stopping. (b) What is the coefficient of friction at the stopping point? (c) How far would the box have slid iff the friciton coefficient didn't increase, but instead had the constant value of .1?
A floating ice block is pushed through a displacement d=(15m)i-(12m)j along a straight embankment by rushing water, which exerts a force F=(210N)i-(150N)j on the block. How much work does theforce do on the block during the displacement?
In the figure below, the rolling axle, 1.43 m long, is pushed along horizontal rails at a constant speed .
A resistor ohm is connected to the rails at points a and b, directly opposite each other. (The wheels make good electrical contact with the rails, and so the axle, rails, and R form a closed-loop circuit. The only significant resistance in the circuit is R.) There is a uniform magnetic field vertically downward. Calculate the induced current I in the resistor and what horizontal force F is required to keep the axle rolling at constant speed?
Find the tension in each cord in Figure if the weight ofthe suspended object is w.
a)
b)
Four point charges form a square with sides of length d, as shown in the figure. In the questions that follow, use the constant k in place of .
Part A
What is the electric potential at the center of the square?
Make the usual assumption that the potential tends to zero far away from a charge.
Express your answer in terms of q ,d, and appropriate constants.
Part B
What is the contribution to the electric potential energy of the system, due to interactions involving the charge 2q ?
Express your answer in terms of q, d, and appropriate constants.
Part C
What is the total electric potential energy of this system of charges? Express your answer in terms of q, d, and appropriate constants.
, plz i want just the final answers , thanks
The initial velocity of a car, vi, is 45 km/h in the positivex direction. The final velocity of the car, vf, is 66 km/h indirection that points 75 degrees above the positive x axis.
a) sketch the vectors -vi, vf and change in v. (b) findthe magnitude and direction in change of velocity.
For b..my answer was -37.93 km/h and -88.41 degrees for direction.