In the figure, a 3.97 g ice flake is released from the edge of a hemispherical bowl whose radius ris 13.7 cm. The flake-bowl contact is frictionless. (a) How much work is done on the flake by the gravitational force during the flake's descent to the bottom of the bowl? (b) What is the change in the potential energy of the flake-Earth system during that descent? (c) If that potential energy is taken to be zero at the bottom of the bowl, what is its value when the flake is released? (d) If, instead, the potential energy is taken to be zero at the release point, what is its value when the flake reaches the bottom of the bowl? Ice flake-

Judy has started fast walking for half an hour each day in an effort to lose weight. Judy currently weighs 100 kg. She walks expending about 0.1 kcal per kg of body weight per minute. For a woman, we multiply the body weight in kg by 0.9 kcal/kg body weight/hour to calculate her BMR. What is Judy’s daily energy expenditure? (Ignore TEF due to its small portion)?

A 7.80-g bullet moving at 560 m/s penetrates a tree trunk to a depth of 5.80 cm. (a) Use work and energy considerations to find the average frictional force that stops the bullet. (b) Assuming the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.

A 7.80-g bullet moving at 470 m/s penetrates a tree trunk to a depth of 6.50 cm. (a) Use work and energy considerations to find the average frictional force that stops the bullet. (b) Assuming the friction force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment in stops moving.

You drop a 1.50 kg book to a friend who stands on the ground at distance D= 12.0 m below. If your friend's outstretched hands are at distance d = 1.30 mabove the ground (see the figure), (a) how much work W, does the gravitational force do on the book as it drops to her hands? (b) What is the change AU in the gravitational potential energy of the book-Earth system during the drop? If the gravitational potential energy Uof that system is taken to be zero at ground level, what is U (c) when the book is released and (d) when it reaches her hands? Now take U to be 100 J at ground level and again find (e) W, (f)AU. (g) U at the release point, and (h) U at her hands. (a) Number Units (b) Number Units (c) Number Units (d) Number Units (e) Number Units (f) Number Units (g) Number Units (h) Number Units >

In the figure, a 3.97 g ice flake is released from the edge of a hemispherical bowl whose radius ris 13.7 cm. The flake-bowl contact is frictionless. (a) How much work is done on the flake by the gravitational force during the flake's descent to the bottom of the bowl? (b) What is the change in the potential energy of the flake-Earth system during that descent? (c) If that potential energy is taken to be zero at the bottom of the bowl, what is its value when the flake is released? (d) If, instead, the potential energy is taken to be zero at the release point, what is its value when the flake reaches the bottom of the bowl? (a) Number (b) Number -5.34e-3 (c) Number 5.34e-3 (d) Number 5.34e-3 Units Units Units Ice flake- Mik Units J

(a) A block with a mass m is pulled along a horizontal surface for a distance x by a constant force F at an angle e with respect to the horizontal. The coefficient of kinetic friction between block and table is u. Is the force exerted by friction equal to u, mg? If not, what is the force exerted by friction? (Assume 0 is measured above the horizontal.) This answer has not been graded yet. (b) How much work is done by the friction force and by F? (Don't forget the signs. Use the following as necessary: F for the magnitude of F, g, m, x, 0 and u,) WE = (c) Identify all the forces that do no work on the block. (Select all that apply.) O friction f OF Cos(e) OF sin(0) O mE (d) Let m = 2.00 kg, x = 4.50 m, 0 = 3.7°, F = 14.5 N, and u, = 0.400, and find the answers to parts (a) and (b). (Include appropriate signs.) We = W =

A child of mass m = 16 kg slides down a slide of height h = 2.7 m without friction. Let gravitational potential energy be zero at ground level. a)Write an expression for the child's total mechanical energy, E, at the top of the slide, in terms of the variables in the problem and the acceleration due to gravity g.  b)Calculate the change in the child's potential energy, ΔU in joules, from the top to the bottom of the slide at ground level (i.e. ΔU = Uground - Utop).  c)What is the child's final speed, vf in m/s?

A child of mass m = 27 kg slides down a slide of height h = 2.1 m without friction. Let gravitational potential energy be zero at ground level. Write an expression for the child's total mechanical energy, E, at the top of the slide, in terms of the variables in the problem and the acceleration due to gravity g.  Calculate the change in the child's potential energy, ΔU in joules, from the top to the bottom of the slide at ground level (i.e. ΔU = Uground- Utop).  What is the child's final speed, vf in m/s?

You drop a 2.50 kg book to a friend who stands on the ground at distance D-13.0 m below. If your friend's outstretched hands are at distance d-1.60 m above the ground (see the figure), (a) how much work W, does the gravitational force do on the book as it drops to her hands? (b) What is the change AU in the gravitational potential energy of the book-Earth system during the drop? If the gravitational potential energy U of that system is taken to be zero at ground level, what is U (c) when the book is released and (d) when it reaches her hands? Now take U to be 100 J at ground level and again find (e) W. (f) AU, (g) U at the release point, and (h) U at her hands. 10000 El