explain step by step please
1) A projectile returns to its original height after 4.08 seconds, during which time it travels 76.2 meters horizontally. If air resistance can be neglected, what was the projectile's initial speed?
(Use g = 9.80 m/s2)
In: Physics
When we receive an X-ray at the dentist office why do they place a lead apron on our chest? Why is it lead? What type of radiation?
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A parallel plate capacitor with plate area 100.0cm2 and air-gap separation .500mm is connected to a 12.0 V battery, and fully charged. The batter is then disconnected.
A.) The plates are now pulled to a separation of 1.00mm. What is
the magnitude of the charge on each capacitor plate and the
magnitude of the E-field between the plates now? (
?0 = 8.85 x 10-12
C2/Nm2)
B.) What is the potential difference across the plates now?
C.) How much work was required to pull the plates to their new separation?
D.) If a proton was released from the + plate and hit the - plate, what speed would it have?
Thanks :D
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A 20 g ball of clay traveling east at 3.0 m/s collides with a 30 g ball of clay traveling north at 2.0 m/s. What is the magnitude and direction of initial momentum for each ball before collision? a. What is the momentum of 50 g blob of clay in x? What is the speed in that same direction? b. What is the momentum of 50 g blob of clay in y? What is the speed in that same direction? c. What is the resultant speed of the blob? d. What is direction of the blob?
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A placekicker must kick a football from a point 36.0 m (about 40 yards) from the goal. Half the crowd hopes the ball will clear the crossbar, which is 3.05 m high. When kicked, the ball leaves the ground with a speed of 23.4 m/s at an angle of 48.0° to the horizontal.
(a) By how much does the ball clear or fall short of clearing
the crossbar? (Enter a negative answer if it falls short.)
m
(b) Does the ball approach the crossbar while still rising or while
falling?
rising or falling
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When a small object approaches a much more massive object, the smaller object can be tidally disrupted. The distance of the closest approach before being tidally disrupted is the Roche limit (recall lecture on rings of plan- ets). If the small object is a star and the large object is a supermassive black hole, the Roche limit is given by
rR= 2.4 * RS * (pBH/p*)^(1/3)
where RS is the Schwarzschild radius, ρ̄BH is the average density of the black hole and ρ̄∗ is the average density of the star.
a) Setting the average density of the supermassive black hole equal to its mass divided by the volume contained within the Schwarzschild radius, derive an expression for the mass of a black hole as a function of ρ̄∗ that would have rR = RS.
b) If the Sun were to fall into a supermassive black hole, what maximum mass could the black hole have if the Sun would be tidally disrupted before crossing the event horizon (or RS). Compare your answer with typical supermassive black holes in the galactic nuclei.
c) If the mass of the supermassive black hole exceeded the mass found above, what would be the implication in terms of the energy release of the infalling star? Could infalling stars effectively power AGNs in this case?
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1）On a certain dry sunny day, a swimming pool's temperature would rise by 1.40°C if not for evaporation. What fraction of the water must evaporate to carry away precisely enough heat to keep the temperature constant?
2）A piece of iron block moves across a rough horizontal surface before coming to rest. The mass of the block is 3.3 kg, and its initial speed is 3.2 m/s. How much does the block's temperature increase, if it absorbs 74% of its initial kinetic energy as internal energy? The specific heat of iron is 452 J/(kg · °C).
°C
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A load of bricks of mass M = 185 kg is attached to a crane by a cable of negligible mass and length L = 3.19 m. Initially, when the cable hangs vertically downward, the bricks are a horizontal distance D = 1.39 m from the wall where the bricks are to be placed. What is the magnitude of the horizontal force that must be applied to the load of bricks (without moving the crane) so that the bricks will rest directly above the wall?
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PLEASE, I NEED CORRECT ANSWERS TO ALL THE QUESTION. THEY ARE MULTIPLE CHOICE QUESTIONS. THANK YOU
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Problem 10.1(b) |
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Problem: Far from the source, the magnitudes of the electric and magnetic acceleration fields are related by which expression?: |
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Problem 10.1(c) |
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Problem: Far from the source, the direction of the threads of an accelerating source is which of the following? |
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A. along the head line |
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Problem 10.2 |
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Problem: In a laser beam, the electric field points upward and the magnetic field points to the east at a fixed time. In what direction is the beam traveling? |
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A. north |
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Problem 10.3 |
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Problem: A point charge is traveling along the x-axis in the positive direction. Its speed is slowing down. If a thread is emitted in this process, which of the following is true? |
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A. the tail line is between the x-axis and the head
line. |
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Problem 10.4(a) |
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Problem: A wire carries current along the +x axis. The current is decreasing in time. At a point P along the +y axis the acceleration electric field points in which direction? |
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A. +x |
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Problem 10.4(b) |
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Problem: A wire carries current along the +x axis. The current is decreasing in time. At a point P along the +y axis the acceleration magnetic field points in which direction? |
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A. +x B. –x C. +y |
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Problem 10.5(a) |
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| Purpose: | |
Problem: Electric charge is the source of which of the following? |
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A. electric field with divergence |
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Problem 10.5(b) |
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| Purpose: | |
Problem: Changing magnetic fields are the source of which of the following? |
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A. electric field with divergence |
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Problem 10.5(c) |
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| Purpose: | |
Problem: Faraday's Law describes which of the following? |
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A. divergence of electric field |
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Problem 10.5(d) |
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| Purpose: | |
Problem: Ampere's Law describes which of the following? |
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A. divergence of electric field |
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Problem 10.5(e) |
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| Purpose: | |
Problem: Displacement current is which of the following? |
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A. the current that is displaced from normal current when a
circuit is shifted. |
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In: Physics
A basketball star covers 3.05 m horizontally in a jump to dunk the ball. His motion through space can be modeled precisely as that of a particle at his center of mass. His center of mass is at elevation 1.02 m when he leaves the floor. It reaches a maximum height of 1.95 m above the floor and is at elevation 0.880 m when he touches down again. (a) Determine his time of flight (his "hang time"). (b) Determine his horizontal velocity at the instant of takeoff. m/s (c) Determine his vertical velocity at the instant of takeoff. m/s (d) Determine his takeoff angle.
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Choose any 3 questions.
1.) What effect does N have on accurately determining the value of the period? What considerations keep one from allowing N to be very large, for example 1000?
2.) What does it mean for the pendulum to have a small angle? How far does the period (T) of the pendulum differ from the linear model that we used to describe the pendulum as a function of initial angle? Note that for this one you will need to measure the period of a single swing of the pendulum. How can you / did you do this?
3.) How can you investigate the pendulum under the effect of reduced gravity? How might you dilute the effect of gravity on the pendulum?
4.) What are the effects of air friction on the mechanical energy of the pendulum? Study the drop in amplitude of oscillation of the pendulum as a function of time, length, mass, period and initial amplitude.
5.) Define the terms amplitude, frequency, angular frequency, and period as they apply to the pendulum.
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In the annual battle of the dorms, students gather on the roofs of Jackson and Walton dorms to launch water balloons at each other with slingshots. The horizontal distance between the buildings is 38.0 m, and the heights of the Jackson and Walton buildings are, respectively, 15.0 m and 22.0 m. The first balloon launched by the Jackson team hits Walton dorm 2.20 s after launch, striking it halfway between the ground and the roof. Ignore air resistance. (a) Find the direction of the balloon's initial velocity. Give your answer as an angle (in degrees) measured above the horizontal. (b) A second balloon launched at the same angle hits the edge of Walton's roof. Find the initial speed of this second balloon.
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Light weight charged bodies stick to neutral matter. Why?
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A QL = -22 ?C charge is placed on the x-axis at x = - 0.4 m. A QR = 22 ?C charge is placed at x = +0.4 m. (for all answers below assume that the unit vector x^ points toward positive x, and y^ points towards positive y.).
a.What is the x-component of the electric field at x = 0 m and y = 0.4m? (N/C)
b. What is the y-component of the electric field at x = 0 m and y = 0.4m? (N)
c What is the x-component of the electric field at x = 0 m and y = -0.4m? (N/C)
d. What is the y-component of the electric field at x = 0 m and y = -0.4m? (N/C)
B and D are 0 but I can't figure out A and C
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