In each cycle of its operation, a heat engine expels 3,900 J of energy and performs 1,900 J of mechanical work. (a) How much thermal energy must be added to the engine in each cycle

- measure reactants precisely. ( first choice)

- stir to the reaction take place. ( second choice)

- wait patiently until the reaction completes. ( fourth choice)

- make sure to recover as much copper as possible. ( last choice)

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards

it's a b and