Question

Can someone please help me with 18 and 19

at the bottom of the hill? Answer in units of m/s 017 10.0 points A pendulum bob is released from some initial height such that the speed of the bob at the bottom of the swing is 2.1 m/s. The acceleration of gravity is 9.81 m/s2 What is the initial height of the bob? Answer in units of m. m. 018 (part 1 of 2) 10.0 points he rope A 1.74x 10 kg car accelerates uniformly from t is the rest to 11.7 m/s in 3.57 s. he mass What is the work done on the car in this time interval? Answer in units of J 019 (part 2 of 2) 10.0 points What is the power delivered by the engine in this time interval? lever is Answer in units of W. 020 (part 1 of 2) 10.0 points A 19.2 kg block is dragged over a rough, hor- izontal surface by a constant force of 200 N acting at an angle of 28.9 above the horizon- tal. The block is displaced 66.8 m, and the coefficient of kinetic friction is 0.237. er. e of 75 N or e did. 19.2 kg

Answer 1

Using work - energy theorem: work done = change in kinetic energy = K_f - K = 1/2 m (V^2 - U^2) = 1/2 times 1.74 times 10^3 (11.7)^2 - 0^2} = 1/2 times 1.74 times 10^3 times 11.7 times 11.7 = 119.0943 times 10^3 Joules power delivered = work done/time = 119.0943 times 10^3/3.57 = 33.36 w times 10^3 = 33.36 times 10^3 w