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Alja Gradisnik

Alja G.

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Questions asked

INSTANT ANSWER

The recommended daily intake for the average person is about 2200 calories. In 2014, the average American consumed about 3800 calories dailya) With what average power would the average American have to work with in order to consume excess-daily calories? Consider 1 calorie = 4, 18J.b) For how many 20 cm high stairs would a 70 kg man have to climb to burn 1600 calories for it? Ignore the change in thermal energy.(c) How many steps must be climbed if changes of thermal energy are not ignored, but consider that 30% of wasted (chemical) energy are used for the climb?

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INSTANT ANSWER

Two logs with masses m1 and m2 are connected by a very light rope that goes through a very light pulley (see picture below). The friction in the pulley is negligible. The first log rests on a rough table, 2. log hangs over the edge of the table. ktr is the coefficient of friction between the 1st log and the table (suppose that the coefficient of adhesion is equal to the coefficient of friction). The 1st body is also connected to the spring by a coefficient springs k. In the initial state, the spring is not tensioned, the second log is held in the air. When the 2. the body is lowered, it only moves a distance d before it stops (final state: when it stops). (a) Explain why the 2nd log eventually stops? (b) Select a system and display the process with an energy bar chart. (c) Derive a mathematical expression for the distance d that will depend on m1, m2, ktr and k. Evaluate the obtained term by considering extreme cases (maximum, minimum values) and dimensional analysis (ie check that the units on the left correspond to the units on the right sides of the expression).

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INSTANT ANSWER

The recommended daily intake for the average person is about 2200 calories. In 2014, the average American consumed about 3800 calories daily(a) With what average power would the average American have to work with in order to consume excess-daily calories? Consider 1 calorie = 4, 18J.(b) For how many 20 cm high stairs would a 70 kg man have to climb to burn 1600 calories for it? Ignore the change in thermal energy.(c) How many steps must be climbed if changes of thermal energy are not ignored, but consider that 30% of wasted (chemical) energy are used for the climb?

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ANSWERED

Hubert Agamasu verified

Numerade educator

for each of the examples below, identify all the external forces acting on the system, and for each of these forces, write down what their work is (positive, negative, or equal to 0) a.) The football player kicks the ball in the air. The system includes the ball and the Earth b.) A board that slides on a flat surface is stopping. The system includes a board and a surface c.) The wooden board rests on a level surface. The system includes the Earth and the board d.) John rolls a ball. The system includes John, the ball, the Earth, and the surface

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ANSWERED

Supratim Pal verified

Numerade educator

Peter decided to rake the garden next to the house. He used a 3 kg shovel. On average, with one swing, he covers a square of soil 20 cm long, 15 cm wide and 30 cm deep. He raises the shovel with the soil by 40 cm (ie from the initial position of the soil: 15 cm below the soil surface, to the maximum height: 25 cm above the soil surface) and turn the soil. a) How much work does Peter do to rake a rectangular beam 4 m long and 3 m wide? The density of the soil is 1500 kg / m3 b) With what power does he work if he does the work in one hour

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ANSWERED

Umar Sohail Qureshi verified

Numerade educator

Two logs with masses m1 and m2 are connected by a very light rope that goes through a very light pulley (see picture below). The friction in the pulley is negligible. The first log rests on a rough table, 2. log hangs over the edge of the table. ktr is the coefficient of friction between the 1st log and the table (suppose that the coefficient of adhesion is equal to the coefficient of friction). The 1st body is also connected to the spring by a coefficient springs k. In the initial state, the spring is not tensioned, the second log is held in the air. When the 2. the body is lowered, it only moves a distance d before it stops (final state: when it stops). (a) Explain why the 2nd log eventually stops? (b) Select a system and display the process with an energy bar chart. (c) Derive a mathematical expression for the distance d that will depend on m1, m2, ktr and k. Evaluate the obtained term by considering extreme cases (maximum, minimum values) and dimensional analysis (ie check that the units on the left correspond to the units on the right sides of the expression).

View Answer
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INSTANT ANSWER

The recommended daily intake for the average person is about 2200 calories. In 2014, the average American consumed about 3800 calories daily(a) With what average power would the average American have to work with in order to consume excess-daily calories? Consider 1 calorie = 4, 18J.(b) For how many 20 cm high stairs would a 70 kg man have to climb to burn 1600 calories for it? Ignore the change in thermal energy.(c) How many steps must be climbed if changes of thermal energy are not ignored, but consider that 30% of wasted (chemical) energy are used for the climb?

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ANSWERED

Manish Jain verified

Numerade educator

1 2

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ANSWERED

Mahipal Kumawat verified

Numerade educator

A Frisbee gets stuck in a tree. You want to get it out by throwing a 1.0-kg rock straight up at the Frisbee. If the rock’s speed as it reaches the Frisbee is 4.0 m/s, what was its speed as it left your hand 2.8 m below the Frisbee? Specify the system and the initial and final states and draw energy bar charts.

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