#### Science - 2017-18

# PS.10 c-d - Work, Force, & Power

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

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

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

*Adopted: 2010*

### BIG IDEAS

- Work is done when an object is moved by a force.
- Machines make complicated tasks easier to perform.

- I can explain why simple machines, such as a ramp (inclined plane), are useful.
- I can design a roller coaster

### UNDERSTANDING THE STANDARD

- 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

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: Nov 24, 2017*