Average Speed vs. Instantaneous Speed

Thread starter Natko
Start date Feb 6, 2014
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Average Average speed Speed

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In the scenario of a book falling, the instantaneous speed just before it lands is greater than its average speed throughout the fall. This is due to the acceleration of the book under the influence of gravity, which increases its speed as it descends. The average speed is calculated by dividing the total distance by the total time taken, while instantaneous speed measures the speed at a specific moment. Therefore, since the book accelerates during the fall, the instantaneous speed at the moment before impact exceeds the average speed. Understanding this distinction is crucial in physics.

Feb 6, 2014

Natko

Homework Statement

A book falls off a shelf and lands on the floor. Which is greater, the book's average speed or its instantaneous speed right before it lands?

Homework Equations

v = d/t

The Attempt at a Solution

I think its the instantaneous speed because the book accelerates over time.

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Feb 6, 2014

Ace.

you are right

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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