A metal tool is sharpened by being held against the rim of a wheel on a grinding machine by a force of 180 N. The frictional forces between the rim and the tool grind off small pieces of the tool. The wheel has a radius of 20.0 cm and rotates at 2.50 rev/s. The coefficient of kinetic friction between the wheel and the tool is 0.320. At what rate is energy being transferred from the motor driving the wheel to the thermal energy of the wheel and tool and to the kinetic energy of the material thrown from the tool?

A 500 kg cart rests atop a hill 30.0 m high on a roller coaster. Its gravitational potential energy is measured relative to the bottom of the hill. The cart then rolls down the hill. Which of these best describes what is happening in this situation?   a. the total mechanical energy of the cart is decreasing, the kinetic energy of the cart is increasing, and the gravitational potential energy of the cart is increasing   b. the total mechanical energy of the cart is increasing, the kinetic energy of the cart is increasing, and the gravitational potential energy of the cart is increasing   c. the total mechanical energy of the cart is increasing, the kinetic energy of the cart is increasing, and the gravitational potential energy of the cart is decreasing   d. the total mechanical energy of the cart is increasing, the kinetic energy of the cart is decreasing, and the gravitational potential energy of the cart is increasing   e. the total mechanical energy of…

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

2 W S X In a hydroelectric dam, water falls 35 m and then spins a turbine to generate electricity. 3 E D 80 C $ 4 R 888 F V 96 5 T G ^ 6 B ▾ Part A What is AU of 1.0 kg of water? Express your answer with the appropriate units. View Available Hint(s) AU= -340 J Y Submit ▾ Part B ✓ Correct SOLVE: The change in the potential energy of 1.0 kg of water in falling 35 m m is H Suppose the dam is 80% efficient at converting the water's potential energy to electrical energy. How many kilograms of water must pass through the turbines each second to generate 48 MW of electricity? This is a typical value for a small hydroelectric dam. Express your answer in kilograms per second. ▸ View Available Hint(s) m 11s AU, -mgh=-(1.0 kg) (9.8 m/s²) (35 m) = -340 J = = Provide Feedback Submit MacBook Air Previous Answers & 7 N IG] ΑΣΦ | 3-4 U * 8 D-H I M @ JK ( 9 MOSISO DD O I भ ? O L kg/s command F10 P > ; C option + ? T I Next > delete re

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Energy conservation with conservative forces: A very small 100-g object is attached to one end of a massless 10-cm rod that is pivoted without friction about the opposite end. The rod is held vertical, with the object at the top, and released, allowing the rod to swing. What is the speed of the object at the instant that the rod is horizontal? 1.8 m/s 1.4 m/s 0.71 m/s 2.8 m/s 4.0 m/s fbb

A 10.0-kg bob is attached to a rod whose length is 10.0 m. The right end of the rod is fixed, and the bob is released from rest. a) Determine the speed of the bob when it is below the pivot point (vertical angle is zero). b) Determine the tension in the rod when the bob is below the pivot point. hint: to determine the speed of the bob when it is below the pivot point, you will need to use Calculus.

A 5 kg object is fired straight up with an initial speed of 100 m/s. Ignore air resistance and set the initial height of the object at zero. Use g = 10m/s/s.   Find the total energy of the object. Find the height of the object when its speed is 50 m/s. Find the speed of the object when its height is 80 m. Find the maximum height of the object.   A child and sled have a combined mass of 50 kg. The child starts sliding from rest at the top of a 10 m high hill. On the way down, friction reduces the total energy by 3000 J. What is the child's speed at the bottom of the hill?

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Situation 02. A crate has a mass of 120kg and the coefficient of static and kinetic friction is 0.60 and 0.50, respectively. The crate starts from rest and the motor exerts a tension T= 1220 + 200t (N). If the elevation of the dock is 30 degrees from the horizontal, a. What is the velocity of the crate after 1sec? b. Compute the power transmitted after 1sec.