When it rises to a certain point P, the kinetic energy is reduced to 10J, and the mechanical energy is lost by 10J. If the air resistance is constant, the object will be ejected vertically When it rises to a certain point P, the kinetic energy is reduced to 10J, and the mechanical energy is lost by 10J. If the air resistance is constant, then the air resistance is stable The gravitational potential energy at the highest point is? The answer is 40J What is the kinetic energy when landing? The answer is 20j Wrong type correction: throw the object vertically with the initial kinetic energy of 60j. When it rises to a certain point P, the kinetic energy is reduced by 30J, and the mechanical energy is lost by 10J. If the air resistance remains unchanged, then

When it rises to a certain point P, the kinetic energy is reduced to 10J, and the mechanical energy is lost by 10J. If the air resistance is constant, the object will be ejected vertically When it rises to a certain point P, the kinetic energy is reduced to 10J, and the mechanical energy is lost by 10J. If the air resistance is constant, then the air resistance is stable The gravitational potential energy at the highest point is? The answer is 40J What is the kinetic energy when landing? The answer is 20j Wrong type correction: throw the object vertically with the initial kinetic energy of 60j. When it rises to a certain point P, the kinetic energy is reduced by 30J, and the mechanical energy is lost by 10J. If the air resistance remains unchanged, then

The increase of gravitational potential energy is equal to the decrease of kinetic energy and mechanical energy is equal to 30-10 = 20j, the height of rise is h = 20 / Mg, the resistance is f = w / h = 10 / 20 / Mg = 1 / 2mg (where w = Δ e, i.e. the decrease of mechanical energy) rises from the beginning to the highest point

A machine has done a total of 8000j of work, of which the extra work is 13% of the active work, so what is the active work of this machine___ What is the mechanical efficiency___ ．

W you + W amount = w total, w you + 13W you = 8000j, so w you = 6000J, η = w you, w total = 6000J, 8000j = 75%

The mechanical efficiency of a pulley block is 60%. If the extra work is 100 J, the total work is 100 J______ J. It's hard work______ J．

Let the work be w useful, ∵ w extra = 100J, ∵ wtotal = w useful + W extra = w useful + 100J, and ∵ η = 60%, ∵ wtotal = w useful, ∵ η = (W useful + W extra) × η, and substitute the value to get w useful = (W useful + 100J) × 60%, and simplify the formula to get w useful = 0.6 × w useful + 60j, so w useful = 150j. ∵ wtotal = w useful + W extra = 150j + 100J = 250j

The mechanical efficiency of a pulley block is 60%. If the extra work is 100 J, the total work is 100 J______ J. It's hard work______ J．

Let W be useful, ∵ w extra = 100J, ∵ w total = w useful + W extra = w useful + 100J, and ∵ η = 60%, ∵ w useful = w total ∵ η = (W useful + W extra) × η, substituting the value into w useful = (W useful + 100J) × 60%, and simplifying the formula: W useful = 0.6 × w useful + 60j, so w useful = 150