合力：练习题

A toy car is pushed with a forward driving force of \(12\text{ N}\). At the same time, a frictional force of \(4\text{ N}\) acts in the opposite direction. What is the size of the resultant force acting on the car?

A ball with a mass of \(0.5\text{ kg}\) is falling through the air. At a specific point in its descent, it experiences an air resistance force of \(2.0\text{ N}\). If the gravitational field strength \(g\) is \(10\text{ N/kg}\), what is the size and direction of the resultant force acting on the ball?

A wooden crate with a mass of \(20\text{ kg}\) is pulled across a rough horizontal floor by a constant horizontal force of \(80\text{ N}\). The frictional force opposing the motion is \(30\text{ N}\). What is the acceleration of the crate?

According to Newton’s First Law, what happens to a moving object if the resultant force acting on it is zero?

An elevator of mass \(800\text{ kg}\) is being pulled upwards by a cable. The elevator accelerates upwards at a constant rate of \(1.5\text{ m/s}^2\). Taking the gravitational field strength \(g\) as \(10\text{ N/kg}\), what is the tension in the cable?

A resultant force of \(50\text{ N}\) acts on an object with a mass of \(10\text{ kg}\). Calculate the acceleration of the object in \(m/s^2\).

Two forces act on a stationary point: a force of \(3.0\text{ N}\) acting vertically upwards and a force of \(4.0\text{ N}\) acting horizontally to the right. Use a vector diagram or calculation to determine the magnitude of the resultant force.

A crate of mass \(50\text{ kg}\) is being pulled across a flat floor by two ropes. Rope 1 pulls with a force of \(300\text{ N}\) due North. Rope 2 pulls with a force of \(400\text{ N}\) due East.
(a) Calculate the magnitude of the resultant force acting on the crate.
(b) Determine the direction of the resultant force as a bearing from North.
(c) Calculate the acceleration of the crate, assuming there are no other horizontal forces acting on it.