Answer:
4054.26 J
Explanation:
Given:
mass of water-skier 'm'= 84.0 kg
Initial velocity 'vi'= 7.4m/s
Final velocity 'vf'= 12.3 m/s
workdone 'W'= ?
As we know that the change in the kinetic energy of an object is equal to the net work done on the object. This fact is referred to as the Work-Energy Principle.
W = Δ K. E---> eq(1)
Kinetic energy K.E= 1/2 mv²
where m=mass of an object and v= velocity
eq(1)=> W= K.E(final)- K.E (initial)
W= 1/2 mvf² - 1/2 mvi²
W= 1/2 x 84 (12.3² - 7.4² )
W= 1/2 x 84 x 96.53
W=4054.26 J
Therefore, the work done by the net external force acting on the skier is 4054.26 J
Answer:
Net work = 4054.26J
Explanation:
We are given that;
mass of water-skier; m= 84 kg
Initial speed; v_i = 7.4m/s
Final speed v_f= 12.3 m/s
Kinetic energy of mass moving with velocity is; KE = (1/2)mv²
From work energy theorem, the net work done on an object is equal to the difference between the initial and final kinetic energy of that object.
Thus,
W = KE_f - KE_i
W = (1/2)mv_f² - (1/2)mv_i²
Plugging in the relevant values to get ;
W = (1/2)(84)(12.3²) - (1/2)(84)(7.4)²
W = 4054.26J
