# PS.10 - Work, Force, & Motion

The student will investigate and understand the scientific principles of work, force, and motion. Key concepts include

a) speed, velocity, and acceleration;

b) Newton’s laws of motion;

c) work, force, mechanical advantage, efficiency, and power; and

d) technological applications of work, force, and motion.

Bloom's Levels:  Analyze; Understand

### BIG IDEAS

• Motion is a key characteristic of all matter that can be observed, described, and measured.
• Energy change can be understood in terms of forces- pushes or pulls.
• Work is done when an object is moved by a force.
• Machines make complicated tasks easier to perform.

• I can determine how fast a car is moving.
• I can explain why, when two objects collide, they often bounce backwards.
• I can explain why simple machines, such as a ramp (inclined plane), are useful.
• I can design a roller coaster.

### UNDERSTANDING THE STANDARD

• Acceleration is the change in velocity per unit of time. An object moving with constant velocity has no acceleration. A decrease in velocity is negative acceleration or deceleration. A distance-time graph for acceleration is always a curve. Objects moving with circular motion are constantly accelerating because direction (and hence velocity) is constantly changing.
• Newton’s three laws of motion describe the motion of all common objects.
• Mass and weight are not equivalent. Mass is the amount of matter in a given substance. Weight is a measure of the force due to gravity acting on a mass. Weight is measured in newtons.
• A force is a push or pull. Force is measured in newtons. Force can cause objects to move, stop moving, change speed, or change direction. Speed is the change in position of an object per unit of time. Velocity may have a positive or a negative value depending on the direction of the change in position, whereas speed always has a positive value and is nondirectional.
• Work is done when an object is moved through a distance in the direction of the applied force.
• A simple machine is a device that makes work easier. Simple machines have different purposes: to change the effort needed (mechanical advantage), to change the direction or distance through which the force is applied, to change the speed at which the resistance moves, or a combination of these. Due to friction, the work put into a machine is always greater than the work output. The ratio of work output to work input is called efficiency.
• Mathematical formulas are used to calculate speed, force, work, and power.

### ESSENTIALS

In order to meet this standard, it is expected that students will

a)  make measurements to calculate the speed of a moving object.

apply the concepts of speed, velocity, and acceleration when describing motion.

b)  identify situations that illustrate each Law of Motion.

c)  explain how force, mass, and acceleration are related.

apply the concept of mechanical advantage to test and explain how a machine makes work easier.

make measurements to calculate the work done on an object.

make measurements to calculate the power of an object.

solve basic problems given the following formulas:

Speed = distance/time (s = d/t)

Force = mass × acceleration (F = ma)

Work = force × distance (W = Fd)

Power = work/time (P = W/t).

d)  explain how the concepts of work, force, and motion apply to everyday uses and current technologies.

a-d) differentiate between mass and weight.

### KEY VOCABULARY

speed, velocity, acceleration, Newton's Laws of Motion, work, force, mechanical advantage, efficiency, power, mass, weight, simple machines, compound machine

Updated: Jun 29, 2018