answer all the questions

Question 1 (1 point] A ball is being twirled in a circle at the end of a string. The string provides the centripetal force needed to keep the ball moving in a circle at constant speed. What is the sign of the work done by the string on the ball in this situation? .1\" zero, the string does no work .g' :3. positive .f negative Question 2 (1 point) Which requires more work: lifting a 7-kg rock to a height of 1.8 m without acceleration or accelerating the same rock horizontally from rest to a speed of 6 m/s? Lifting the rock without acceleration requires more work. C Both cases require the same amount of work Accelerating the rock horizontally from rest to a speed requires more work.Question 3 (1 point) A child and sled with mass of 47.9 kg slide down a hill with a height of 2.61 m. If the sled starts from rest and has a speed of 4.6 m/s at the bottom, how much thermal energy in units of joules is lost due to friction. (This will be the work done.) (use g=9.8 m/s and be accurate to 2 decimals) Your Answer: AnswerQuestion 4 (1 point) A 41.5 kg woman runs up a flight of stairs in 5 5. Her net upward displacement is 5 m. What power did the woman exert while she was running |[in units ofW and to 2 decimals using g=9.81 [Ti/S2}? Your Answer: Answer Question 5 (1 point) A child and sled with mass of 48.5 kg slide down a frictionless hill. If the sled starts from rest and has a speed of 6.00 m/s at the bottom, how high is the hill in meters to 3 decimals? [use g: 9.81 m/s2) l3 Your Answer: Answer Question 6 (1 point} Consider the three different frictionless ramps shown below. You push an identical box up each ramp at a constant speed of 2.0 mfs. What is the work done by the Normal force in units OH and to 1 decimal point? Your Answer: Answer Question 7 (1 point} A rope applies a horizontal force of 220 N to pull a crate a distance of 6 m across the floor. A frictional force of 110 N opposes this motion. What is the work done by the force applied by the rope in units of J? Question 3 (1 point} In which of the following systems is the work done by a frictional force resulting in the increase of the total mechanical energy of a system? (HT. a car with positive acceleration (HT. a skidding car with negative acceleration 13\"") none Question 9 (1 point} A pendulum is pulled back from its equilibrium {center} position and then released. When the bob is halfway between the high point and the low point in its swing in what formlsl is the total energy of the bob? (:1 potential only [:1 partially kinetic, partially potential [a] kinetic only Question 10 (1 point) woman uses a pulley arrangement to lift a heavy crate. She applies a force that is one-forth the weight of the crate but moves the rope a distance four times the height that the crate is lifted. How does the work done by the woman on the rope compare to the work done by the rope on the create it there are no dissipative forces? 0 the work done by the woman is equal 0 the work done by the woman is greater 0 the work done by the woman is less