Can you help me with these questions? I have formulas but idont know if my answe

Question

Can you help me with these questions? I have formulas but idont know if my answers are correct. I.A water skier whose mass is 70 kgg has a initial speedof 40 m/s. ater on, the speed of the skier is 67.0 m/s. a.) Howmuch work was done by the net force acting on the skier?b.)Calculate the change in kinetic energy of the skier. II. A 1.2 kg block is held a height of 10 m above the floor.a) calculate work while holding the object at this height. b) Ifthe block is dropped from this height, calculate the kinetic energyand gravitational potential energy of the object when it reaches aheight of 4 m from the floor III. A rope oriented 52 degrees above the horizontal exerts a120 N force on a 10 kg crate while pulling it 10 m along ahorizontal surface. Calculate the work done by the rope on thecrate. Can you help me with these questions? I have formulas but idont know if my answers are correct. I.A water skier whose mass is 70 kgg has a initial speedof 40 m/s. ater on, the speed of the skier is 67.0 m/s. a.) Howmuch work was done by the net force acting on the skier?b.)Calculate the change in kinetic energy of the skier. II. A 1.2 kg block is held a height of 10 m above the floor.a) calculate work while holding the object at this height. b) Ifthe block is dropped from this height, calculate the kinetic energyand gravitational potential energy of the object when it reaches aheight of 4 m from the floor III. A rope oriented 52 degrees above the horizontal exerts a120 N force on a 10 kg crate while pulling it 10 m along ahorizontal surface. Calculate the work done by the rope on thecrate.

Explanation / Answer

(I) . mass m = 70 kg Initial velocity u = 40 m / s final velocity v = 67 m / s (a). work done W = ( 1/ 2) m [ v ^ 2 - u ^ 2]   from work energy theorem                             = 101115 J (b). change in kinetic energy of the skier = workdone                                                              = 101115 J (II) . mass of the block m = 1.2 kg height h = 10 m (a). required work W = m gh                                   = 117.6 J (b). Gravitational potential energy = m g ( 4 )                                                    = 47.04 J kinetic energy = 117.6 -47.04                      = 70.56 J

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