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# Gravity

### Archimedes' Principle

When you are bathing on a stony beach, why do the stones hurt your feet less when you get in deep water?

### Newton's Law of Gravitation

Ocean tides are produced primarily by the gravitational attraction of the Moon. Explain how this attraction gives rise to two tidal "bulges" on opposite sides of the Earth, resulting in two daily high tides and two daily low tides. [hint: Consider the inverse-square relationship of the distance in the gravitational force actin

### Archimedes' Principle, Euler's Equations & Hydrostatic Pressure

Recall the standard vector identity: {see attachment}. ? A body is immersed in water at rest, under gravity. Show from Euler's equations that the pressure is: {see attachment} (Hydrostatic pressure) ? Deduce that the buoyancy force on the body is equal to the weight of water displaced by it. ? A boat floats on a pond.

### Motion Under Gravity Function

The height s (in feet) at the time t (in seconds) of a silver dollar dropped from the top of the Washington monument is s=-16t+555 a.) Find the average velocity on the interval [2,3] b.) FInd the instantaneous velocity when t=2 and when t=3 c.) how long will it take the dollar to hit the ground? d.) Find the velo

### Work & Energy

An elevator cable breaks when a 715 kg elevator is 20.5 m above the top of a huge spring (k = 8.00 104 N/m) at the bottom of the shaft. (a) Calculate the work done by gravity on the elevator before it hits the spring. (b) Calculate the speed of the elevator just before striking the spring. (c) Calculate the amount the

### Exercise Physiology/Kinesiology/Physics Problem

I am trying to calculate the true weight effects of a supine leg press, standing squat, and bench press in supine. Below is communication between my previous physics professor and myself, but it really didn't answer my question. I guess I want to know if there is mathematical way to get 'true' numbers for the actual weight i

### Physics problems

Please see attached file for questions.

### Buoyant Force of Block

A 227-kg block of cement, of density 2.8 x 10^3 kg/m^3, rests on a pedestal in front of the Al Capone Memorial Library. How much did it weigh submerged, while being hauled out of the river (freshwater)?

### Specific Gravity of Metal Objects

A metal object is hung from a scale and found to weigh 10.0 N. It is then lowered into a tank of water and its "weight," measured while its submerged, is found to be 8.00 N. What is its specific gravity?

### Density of Water Over Uranium

The density of uranium is 18.7 x 10^3 kg/m^3. What is it specific gravity? How much more dense than water is uranium?

### Centre of Gravity Homogeneous

Locate the centre of gravity of a homogeneous rod bent in the form of a semi-circular arc from A to B. The rod has a weight of 0.5 lb/ft and the radius of the arc is 2 ft.

### Newton's Laws - Force

A block of mass m=2.0kg is held in equilibrium on an incline of angle=60 degrees by the horizontal force F. a) determine the value of F b) determine the normal force exerted by the incline on the block (ignore friction).

### Static Equillibrium

A trucker needs to weigh a truck that is too long to fit on a platform scale. When the front wheels of the truck are run onto the scale, the scale reads W1. When the rear wheels are run onto the scale so that the front wheels are off, it reads w2. a) Prove that the total weight of the truck is W1+W2. b) Prove that if the truck i

### Flow Rate Through a Water Hose

Two children, Ferdinand and Isabella, are playing with a water hose on a sunny summer day. Isabella is holding the hose in her hand 1.0 meters above the ground and is trying to spray Ferdinand, who is standing 10.0 meters away. To increase the range of the water, Isabella places her thumb on the hose hole and partially covers it

### Equilibrium and Center of Gravity

A 170cm tall person lies on a light (massless) board which is supported by two scales, one under the feet and one beneath the top of the head. The two scales read, respectively, 31.6kg and 35.1 kg. Where is the center of gravity of this person?

### Fluid Statics

The specific gravity of ice is .917, whereas that for seawater is 1.025. What fraction of an iceberg is above the surface of the water? *note- if possible, please explain this in the simplest way you can- i'm not naturally a science kinda gal! Thanks :)

### Center of mass of a cemi-circular thin rod.

Locate center of gravity (x) of homogenous rod bent in the form of a semicircular arc. Rod has a weight per unit length of 0.5 lb/ft. radius of arc is 2ft.

### Coefficient of static friction

Force of static friction between any two surfaces is given by: Ff=Us*N How do you find the mass of the coin(m), gravity(g) (9.8m/sec2) and the angle (30) the flat surface makes with the table; Ff=m.g.sin0 and N=m.g.cos0 using the above expressions of Ff and N and the definition of the force of static fricition,show that the co

### Air pressure, gauge pressure

Hi. Can someone please walk me through how to do the following problem? Suppose that when you ride on your 7.70-kg bike the weight of you and the bike is supported equally by the two tires. If the gauge pressure in the tires is 70.5 lb/in^2 and the area of contact between each tire and the road is 7.13 cm^2, what is your weig

### Equilibrium between gravity and electrostatic field

Two dust particles each of mass 13 ug (10^-6) are floating on a gentle stream of air. what (equal) positive charge would each dust particle have to carry in order that their electrostatic repulsion should exactly balance their gravitational attraction? What is the electrostatic potential energy of the two dust particles each

### Motion in the y direction

I don't know how to approach this problem because I don't think that it will be a trajectory problem since the ball is going straight up in the air. Can you help? (See attachment.)

### Equilibrium and Gravity

In Figure 13-5 (not to scale), a package of mass m hangs from a short cord that is tied to the wall via cord 1 and to the ceiling via cord 2. Cord 1 is at an angle of = 40° with the horizontal. Cord 2 is at angle (theta). a. For what value of theta is the tension in cord 2 minimized?(in degrees) b. In terms of mg, what is

### Gravity field of a hollow planet

A uniform, spherical planet has a spherical space at its center. The radius of the surface of the planet is Rp= 8.9E7 m (8.9 x 10^7 m). The radius of the central hollow space is Rh = 6.2E5 m. The total mass of the planet is M= 7.5E28 kg. The distance from the center to three designated points are: Point a is distance Ra= 9

### Calculating the Force Gravity

Question: A steel block has a volume of 0.08 m^3 and a density of 7,840 kg/m^3, what is the force (fo) gravity acting on the block (the weight) in water? A. 5362.56N B. 6150.64N C. 6700.56N D. 7600.18N

### Find Gravity Field of a Planet and Orbital Speed of a Spacecraft

A cloud of dust in space originally occupies volume V= 3.5 x 10^26 m^3 whose average density D= .0085 kg/m^3. Over many billions of years it contracts to form a uniform spherical planet with radius r=5.5 x 10^6 m. Part a. Find the gravity field, g, at the surface of the planet. Part b. Find the orbital speed v, of a spacecraf

### Newton's universal law of gravity

Accodting to Newton's universal law of gravity, if the separation between to bodies is increased by a factor of three, the gravitational pull each has on the other will be X by a factor of Y ?

### "From the earth to the moon", Jules Verne Physics Problem

In his novel "From the earth to the moon", Jules Verne imagined that astronauts inside a space ship would walk on the floor of the cabin when the force exerted on the ship by the earth was greater than the force exerted by the moon. When the force exerted by the moon was greater he thought the astronauts would walk on the ceili

### Apparent Weightlessness and artificial gravity: moon's motion

The moon orbits the earth at a distance of 3.85 x 10^8 m. Assume that this distance is between the centers of the earth and the moon and that the mass of the earth is 5.98 x 10^24 kg. Find the period for the moon's motion around the earth. Express the answer in days and compare it to the length of a month.

### Working with gravitation - three problems

1. Show by algebraically reasoning that your gravitation acceleration towards an object of mass M a distance d away is a=GM/d^2 and therefore doesn't depend on your mass. 2. Can a satellite coast in a stable orbit in a plan that doesn't intersect the earth center? Defend your answer. (Include 1 or more diagrams) 3. Stude

### Constructing a corbeled arch

Four bricks are to be stacked at the edge of a table, each brick overhanging the one below it, so that the top brick extends as far as possible beyond the edge of the table. (a) To achieve this, show that successive bricks must extend no more than (starting at the top brick)1/2, 1/4, 1/6, and 1/8 of their length beyond the one b