Forces：练习题

A student uses a spring balance to pull a wooden block across four different surfaces: ice, sandpaper, a wooden table, and a glass sheet. On which surface will the spring balance show the highest reading in Newtons (N)?

An object is moving at a constant speed across a flat surface. If the frictional force acting on the object is exactly 10 N, how much pushing force is being applied to keep it moving at that constant speed?

A student uses a force meter (Newton meter) to pull a toy car across a floor. If the student adds heavy weights into the car, what will happen to the reading on the force meter when the car starts to move?

Identify the force that acts against an object moving through water, slowing it down.

A ball is thrown upwards into the air. Name the two main forces acting on the ball while it is moving through the air and state their directions.

Which force is responsible for pulling objects towards the center of the Earth and keeps the moon in orbit?

Forces
A student uses a spring balance to measure the weight of an object in air and then explores the forces acting on a boat in a lake.

(a) What is the standard unit of force?
(b) When a boat is floating stationary on water, there are two main vertical forces acting on it. Name these two forces.
(c) If the boat starts to move forward, what force acts between the boat and the water to oppose its motion?

Forces and Friction
A student is investigating the forces acting on a block of wood as it is pulled across a horizontal table using a spring balance.

(a) What is the name of the force that acts between the surface of the wooden block and the table to oppose its sliding motion?
(b) If the student pulls the block with a force of \(5\) N but the block does not move, what is the magnitude of the opposing force?
(c) The student then covers the table with a layer of oil. How would this affect the force needed to start the block moving? Explain your answer.
(d) Give one example of a situation where increasing this type of force is beneficial in everyday life.