2. Sci 701 Unit 5

3. Speed is a measure of how fast an object is moving, that is, how much distance it will travel over a given time. This measure is given in units distance per time. The formula for speed is:

4. If a toy car takes 7.5 sec to travel 15 m. How fast is it moving? Example:

5. Speed can be expressed rotationally as well. This refers to how fast something is moving in a circle. It is measured in units of angular-distance per time or rotational cycles per time. Common examples include degrees per second or revolutions per minute (RPM).

6. Acceleration A change in speed over time is known as acceleration. The higher the acceleration the faster the change in speed. If something is moving at a constant speed, it is not accelerating.

7. Force Accelerations are caused by forces. When you press on something you are exerting a force on it. When a robot is accelerating it does so because of the force its wheels exert on the floor. Force is measured in units such as pounds and newtons.

8. The formula for force and acceleration is:

9. How much force would it take to accelerate a 30 kg mass at a rate of 2m/s 2 Example:

10. Torque Force directed in a circle is called torque. Torque is a spinning force; however in the instance of a wheel, this spinning force creates a linear force at its edge. This is how we define torque, as a linear force at the edge of a circle. Torque is described by the magnitude of the force multiplied by the distance it is from the center of rotation (Force x Distance = Torque). Torque is measured commonly in units of inch-pounds or newton-meters.

12. If a 25 lb force is applied to the outside edge of a tire with a radius of 8 inches. What torque is being applied? Example: or

13. Work Work is the measure of a force exerted over a distance. If I lift something 5 feet, it requires less work than if I lifted it 10 feet. It can also be thought of as a change in energy. Power Energy that is produced by mechanical, electrical, or other means and used to operate a device. The time-rate of doing work, measured in watts or less frequently horsepower.

14. DC Motor An electric rotating machine energized by direct current and used to convert electric energy to mechanical energy. Direct current (DC) An electric current flowing in one direction only. Shaft Often referred to as a drive shaft. A mechanical device for transferring power from the engine or motor to where it is wanted.