Question

На парашутиста в воздухе действуют 2 силы: сила притяжения Земли , направление которой совпадает с направлением движения парашутиста и которая равна 90Н , и сила сопротивления воздуха, которая направлена против движения парашутиста и тоже равна 90Н. Найдите равнодействующую силу. Опишите характер движения парашутиста.

Answer 1

Равнодействующая равна нулю. Именно поэтому парашЮтист сейчас движется равномерно и прямолинейно - в полнейшем соответствии с первым законом Ньютона. При этом он, естественно, сохраняет ту скорость относительно Земли, которой достиг в процессе замедленного движения (когда раскрытый парашют тормозил падение парашютиста после раскрытия купола).
PS это, надо полагать, игрушечный парашютист? уж больно масса (9 кило) маленькая - судя по силе тяжести в 90 Н. Впрочем, законы природы одинаковы для всех.

Answer 2

Calculation of the Resultant Force

To find the resultant force acting on the parachutist, we need to consider the two forces acting on them: the force of gravity (also known as the weight) and the force of air resistance.

The force of gravity is directed downwards and has a magnitude of 90 N. The force of air resistance is directed opposite to the motion of the parachutist and also has a magnitude of 90 N.

To find the resultant force, we can use vector addition. Since the two forces are equal in magnitude and opposite in direction, they cancel each other out. Therefore, the resultant force is zero.

Character of the Parachutist's Motion

Since the resultant force acting on the parachutist is zero, according to Newton's first law of motion, the parachutist will continue to move with a constant velocity in the same direction as their initial motion. This means that the parachutist will experience a state of equilibrium, where the forces acting on them are balanced.

In this case, the parachutist will continue to fall downwards at a constant speed, without accelerating or decelerating. This is known as terminal velocity, which is the maximum speed that an object can reach when the force of air resistance equals the force of gravity.

It's important to note that the actual motion of a parachutist is influenced by various factors, such as the size and shape of the parachute, the mass of the parachutist, and the atmospheric conditions. These factors can affect the magnitude of the forces and the resulting motion.