A 68.1-kg boy is surfing and catches a wave which gives him an initial speed of 1.60 m/s. He then drops through a height of 1.62 m, and ends with a speed of 8.51

4. A 70 kg skier is traveling at 25 m/s downhill at point A, which is 80 m above the base, as shown. The surface is rough with 4 = .15 and ø= 20°. What is the initial mechanical energy of the skier? b. How fast is she traveling at the bottom of the hill? c. If she continues moving along the horizontal surface with the same 4, how far will she travel before coming to rest? a. A

A 71.1-kg boy is surfing and catches a wave which gives him an initial speed of 1.60 m/s. He then drops through a height of 1.59 m, and ends with a speed of 8.51 m/s. How much nonconservative work (in kJ) was done on the boy?

The above graph shows the potential energy U(x) of a particle as a function of its position x. The total mechanical energy in the system is marked with the dashed horizontal line at 4 Joules. what is the Inventory Initial Energy of this problem? Describe Energy in System at First Critical PointUse Relevant Formats and Tools to Communicate Initial Energy State

1. Boxing gloves are padded to lessen the force of a blow. The glove and face compress 7.5000 cm during a blow in which the 7.0000-kg arm and glove are brought to rest from an initial speed of 10.0000 m/s. ▬▬ - Think & Prepare 1. Make note of what's given and what's unknown. Relate known quantities to symbols. 2. Draw a labeled sketch if possible. 3. Identify the physics principle and approach. Write down relevant equations symbolically. Simplify if possible. 4. Insert numerical quantities to solve for unknowns. 5. Does the answer make sense? % (a) Calculate the change in kinetic energy of the glove and arm. AKE = (b) Where does this energy go? O Search 5 O into doing work against the force exerted by the face against the glove O into doing work against gravity O into the potential energy of the face O into the potential energy of the glove and arm T 4- 6 Y 17 + & J 7 90 8 * 8 U I 이 144 ( 9 110 DII O E DDI I P 2 { 4 ( ← backs

A 71.6-kg boy is surfing and catches a wave which gives him an initial speed of 1.60 m/s. He then drops through a height of 1.61 m, and ends with a speed of 8.51 m/s. How much nonconservative work (in kJ) was done on the boy? kJ

12:45 1 4) A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in the figure. The vertical height above ground level at position A is 200 m. Neglect friction. 200 m 160 m -- Potential Energy 0 A.What is the total mechanical energy of the roller coaster at point A? B. What is the total mechanical energy of the roller coaster at point B? C. What is the speed of the roller coaster at point B? Explain your D. What is the speed of the roller coaster at point C? answer

RELATIONSHIP BETWEEN WORK AND ENERGY Theory: The net work done on an object always produces a change in kinetic energy of the object. Vo P Total work done = AKE Positive work - Negative work = KEinal KEinitial P(S) - F(S) = -mv² -mvo2 21 1. %3D 2 12. What average force is required to stop a bullet of mass 20 grams and speed 250 m/ s as it penetrates wood to a distance of 12 cm?

20- A 65-kg boy is surfing and catches a wave which gives him an initial speed of 1.6 m/s. He then drops through a height of 1.58 m, and ends with a speed of 8.5 m/s. How much nonconservative work (in kJ) was done on the boy?

A crane at a construction site lifts a concrete block with a mass of m = 482 kg from the ground to the top of a building with a height of h = 23.9 m. How much work did the motor of the crane do? (Assume zero energy loss in the lifting mechanism due to friction.) -112894 J moter If the duration of the lift was 1.35 minutes, then what was the average power performed by the crane?