A 65-kg athlete runs at constant speed a distance of 600 m up a mountain inclined at 20° to the horizontal. He perfoms this feat in 80s. Assuming that air resistance is negligible, (a) how much work does he performand (b) what is his power output during the run? 20

An electric scooter has a battery capable of supplying 120 Wh of energy. If friction forces and other losses account for 60.0% of the energy usage, what altitude change can a rider achieve when driving in hilly ter-rain if the rider and scooter have a combined weight of 890 N?

A particle of mass 2.0 kg moves under the influence of the force F(x)=(5x2=7x)N . Suppose a frictional force also acts on the particle. If the particle’s speed when it starts at x=4.0 m is 0.0 m/s and when it arrives at x=4.0 m is 9.0 m/s, how much work is done on it by the frictional force between x=4.0 m and x=4.0 m?

Two forces act to double the speed of a particle, initially moving with kinetic energy of 1 J. One of the forces does 4 J of work. How much work does the other force do?

A cart is pulled a distance D on a flat, horizontal surface by a constant farce F that acts at an angle with the horizontal direction. The other forces on the object during this time are gravity (Fw) , normal forces (FN1) and (FN2) , and rolling frictions Fr1 and Fr2 , as shown below What is the work done by each force?

As a young man, Tarzan climbed up a vine to reach his tree house. As he got older, he decided to build and use a staircase instead. Since the work of the gravitational force mg is path Independent, what did the King of the Apes gain in using stairs?

A baseball of mass 0.25 kg is hit at home plate with a speed of 40 m/s. When it lands in a seat in the left-field bleachers a horizontal distance 120 m from home plate, it is moving at 30 m/s. If the ball lands 20 m above the spot where it was hit, how much work is done on it by air resistance?

In a Coyote/Road Runner cartoon clip (https://openstaxcollege.org/l/21coyroadcarcl), a spring expands quickly and sends the coyote into a rock. If the spring extended 5 m and sent the coyote of mass 20 kg to a speed of 15 m/s, (a) what is the spring constant of this spring? (b) If the coyote were sent vertically into the air with the energy given to him by the spring, how high could he go if there were no non-conservative forces?

A person in good physical condition can put out 100 W of useful power for several hours at a stretch, perhaps by pedaling a mechanism that drives an electric generator. Neglecting any problems of generator efficiency and practical considerations such as resting time: (a) How many people ‘would it take to nm a 4.O0-kW electric clothes dryer? (b) How many people would it take to replace a large electric power plant that generates 800 MW?

Give an example of something we think of as work in everyday circumstances that is not work in the scientific sense. Is energy transferred or changed in form in your example? If so, explain how this is accomplished without doing work.