Kinetic Energy - General Physics - Solved Past Paper, Exams of Physics

Download Kinetic Energy - General Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! 4. (25 pts) A 14 kg block of ice is tossed out the back of a truck and lands on the loading ramp with a speed of 2 m/s. It then slides down the 5 m long ramp and reaches the bottom with a speed of 4.47 m/s. The loading ramp is inclined at 20◦ and has little ridges that cause some friction as the ice block slides over them. 20o 5 m 14 kg a) (5 pts) By how much does the kinetic energy of the ice block change from the top of the ramp to the bottom? Ki = ( 1 2 ) (14)(22) = 28 J Kf = ( 1 2 ) (14)(4.472) = 139.9 J ∆K = Kf −Ki = 139.9− 28 = 112 J b) (5 pts) What is the net work done on the ice block as it travels the 5 m down the ramp? W = ∆K = 112 J c) (5 pts) How much work is done by gravity during this trip? (Hint: Remember that you need the angle between the direction of the force and the direction of motion!) Wg = (mg)(d) cos θ = (14)(9.8)(5) cos(70) = 234.6 J d) (5 pts) Then how much work was done by friction? W = Wg + Wf W = 112 = 234.6 + Wf Wf = −122.6 J e) (5 pts) And finally, how large is the force of friction on the block of ice? Wf = −f d = −(5)f = −122.6 f = 24.5 N