Free-fall Definition and 75 Threads

In free-fall acceleration, how do I figure when "g" is positive or negative? Homework Statement My textbook is confusing me a bit. In general, when would "g" be positive and when would be negative? I thought it was when the particle was falling downward, it was positive and when it's going...

Homework Statement A bolt is dropped from a bridge under construction, falling 85 m to the valley below the bridge. (a) In how much time does it pass through the last 28% of its fall? What is its speed (b) when it begins that last 28% of its fall and (c) when it reaches the valley beneath the...

http://hyperphysics.phy-astr.gsu.edu/hbase/flobi.html" Since the gravitational potential energy of the falling object at the point of impact is higher than the gravitational potential energy at the distance traveled after impact, where does the energy go? It is shown that the KE is removed...

Homework Statement A ball of mass m = 8 kg is dropped from rest at a height h = 13.9 m above the ground. Ignore air resistance. (a)If the ball is being released with a downward speed 4.9 m/s initially, what will be its final speed when it hits the table 0.7 m below the release point? (b)...

Homework Statement The planet Uranus has a mass about 14 times the Earth's mass, and its radius is equal to about 3.7 Earth radii. A)By setting up ratios with the corresponding Earth values, find the free-fall acceleration at the cloud tops of Uranus. B)Ignoring the rotation of the planet...

A ball is thrown upward from the top of a 24.2-m-tall building. The ball's initial speed is 12 m/s. At the same instant, a person is running on the ground at a distance of 29.2 m from the building. What must be the average speed of the person if he is to catch the ball at the bottom of the...

How do you add air resistance to these 2 equations? #1 sqrt(2 * d / g) = time until impact #2 sqrt(2 * d * g) = velocity on impact The equation for air resistance is: Fd = 0.5 * Air Density * Velocity ^2 * Frontal Area * Drag Coefficient How would you combine this equation with the above...

Homework Statement A drowsy cat spots a flowerpot that sails first up and then down past an open window. The pot is in view for a total of 0.50 s, the top-to-bottom height of the window is 2.00 m. How high above the window top does the flowerpot go? Homework Equations Constant...

Homework Statement I have just a question to clarify. When an object is in free-fall the gravity is always + 9.81 m/s^2? and also when it is talking about two dimension kinematics gravity is working on an object thrown in the air it is -9.81 m/s^2? Homework Equations The Attempt at...

Homework Statement From Taylor's "Classical Mechanics", problem 9.15: On a certain planet, which is perfectly spherically symmetric, the free-fall acceleration has magnitude g = g_0 at the North Pole and g = \lambda g_0 at the equator (with 0 \leq \lambda \leq 1). Find g(\theta), the...

Homework Statement An object traveling along the x-axis at constant acceleration has a velocity of +10 ,m/s when it is at x = 6.0 m and of +15m/s when it is at x = 10m What is it acceleration? B)An object projected vertically upward with initial speed of v0 attains a maximum height of h...

Homework Statement A research party on Jupiter in the year 3005 drops a steel ball from 300 meters above ground. It takes exactly 5 seconds to reach the ground. a. Calculate the value of g (the acceleration due to gravity) on the surface of Jupiter. b. What is the velocity of the steel...

Homework Statement hot air balloon traveling vertically upward at 2.2 m/s. at 25 m above ground, releases a package. Solve for t. Homework Equations d=v(initial)t + 0.5(a)t2 The Attempt at a Solution 25m = [0.0 m/s(t)] + ½(9.8m/s2)t2 25/4.9 = t2 t=2.26 seconds My question...

Homework Statement To test the quality of a tennis ball, you drop it onto the floor from a height of 4.00m. It rebounds to a height of 2.00m. If the ball is in contact with the floor for 12.0ms, (a) what is the magnitude of its average acceleration during that contact and (b) is the average...

1. The problem statement A object is dropped into a free-fall from a distance of 3 earthradiuses from the center of the earth. Starting at a velocity of 0. How long time does it take for the object to travel the halv distance to Earth (that would be the length of one EarthRadius), and how long...

Homework Statement A "seconds" pendulum is one that moves through its equilibrium position once each second (period = 2.000 s). The length of a seconds pendulum in Tokyo is 0.9927 m and at Cambridge is 0.9942 m. What is the ratio of the free-fall acceleration at these two locations...

I've spent about an hour and a half on this question, working with different formulas and manipulating equations but I still can't figure it out. The question: "A ball, dropped from rest, covers three-quarters of the distance to the ground in the last second of its fall. From what height was...

I keep trying to get this right but I keep falling short. Here's the problem: A hoodlum throws a stone vertically downward with an initial speed of 19.0 m/s from the roof of a building, 39.0 m above the ground. (a) How long does it take the stone to reach the ground? (b) What is the speed of...

This problem incorporates the main idea of gravitational freefall, but also adds an extra to it, and I get different answers from the back of the book: A rock is dropped from a sea cliff, and the sound of it striking the ocean is heard 3.2s later. If the speed of sound is 340m/s, how high is...

5. Sue is watching Hugh 7.2 meters below her when she sees him throw a ball up to hit her. She pulls in her head, but Hugh purposely threw the ball hard enough to hit her on his way down 1 second after it passes her on the way up. Explain how hugh figured this out... I used a sort of system...

A "seconds" pendulum is one that goes through its equilibrium position once each second. (The period of the pendulum is 2.000 s.) The length of a seconds pendulum is 0.9927 m at Tokyo and 0.9942 m at Cambridge, England. What is the ratio of the free-fall accelerations at these two locations...

Hi, it's my first post. Thanks for letting me join your forums as I learn physics. Here is the problem: A stone is thrown vertically upward at a speed of 35.30 m/s at time t=0. A second stone is thrown upward with the same speed 1.390 seconds later. At what time are the two stones at the...

A rocket on the ground, accelerates straight upward from rest with constant net acceleration "a" , until time "t" , when the fuel is depleted. Here "g" is a positive number equal to the magnitude of the acceleration "a" due to gravity. -What is the maximum height reached in terms of a, t...

A measurement of free-fall acceleration,g, was made by throwing a glass ball straight up in an evacuated tube and letting it return. Let ΔTl be time interval between two passages of ball across a certain lower level, ΔTu the time interval between the two passes across an upper level, and H the...

We have already discussed the definition of g to death, but I have another question regarding the use of "free fall." This is also a term that is misleading, since a body doesn't have to be falling to be truly in free-fall. Can anyone come up with a better term?