If an automobile engine delivers a power of 50.0 hp, how much time will it take for the engine to do 6.40 x 10^4 j of work? (1 hp= 746 w)

Given data

Power (P) = 50 hp,

                = 50 × 746,  we know that 1 hp = 746 W.

                = 37300 Watts      (Watt = J/s)  

Work  = 6.40 ×10⁴ J

Power is defined as rate of doing work and the unit of power is Watt.

Mathematically,

         Power = (Work / time)   Watts

                     = 6.40 ×10⁴ / time

          37300 W = 6.40 ×10⁴ J /time      (Where time in seconds)

         => time = Work/Power

                      = 6.40 ×10⁴/37300

                      = 1.74 seconds  

 Therefore , the engine need 1.74 seconds to do 6.40 6.40 ×10⁴ J of work

chemical energy --> gravitational potential energy --> kinetic energy --> elastic potential energy --> gravitational potential energy

explanation:

when emma starts the hike, the chemical energy stored in her body is used to climb up the mountain, and so she gains gravitational potential energy (because at the end, she will be at a higher height h above the ground). then she goes bungee jumping: as she falls, this gravitational potential energy is converted into kinetic energy (because her speed increases as she falls down), until the point when the rope stretches, and she stops moving. at that moment, all the kinetic energy is converted into elastic potential energy due to the stretching of the rope. then, this energy is released because the rope returns to its natural length, and emma gains a small increase in altitude , so she gains some gravitational potential energy.