Science Starter How would you describe motion? *Do Not use the terms move, moving or movement in your answer!
Science Starter The speed of an animal is how fast it is moving. A speed of 6 m/s (meters per second) means that the animal moves a distance of 6 meters every second. How would you measure the speed of an animal? What do you think are the fastest animals?
Introductory Video Physical Science: Motion etId=1cedd218-43c5-42ee e427dc1 etId=1cedd218-43c5-42ee e427dc1
Motion Motion: a change in position in a certain amount of time
Speed Speed: the rate at which an object moves Anything that is changing its position has speed Example: ocean currents, the moon, a car, a person walking
Speed Formula: speed = distance time Constant Speed: speed that does not change This is shown a straight diagonal line on a distance-time graph Average Speed: dividing the total distance by the total time
Measuring Motion Sample problem: At what speed did a plane fly if it traveled 1760 meters in 8 seconds? Step 1 – Write the formula. Speed = Distance/Time Step 2 – Substitute given numbers and units. Speed = 1760 meters/8 seconds Step 3 – Solve for the unknown. Speed = 220 meters/second (m/sec)
Measuring Motion Practice Problems: 1. A car travels 240 kilometers in 3 hours. What is the speed of the car during that time? 2. The speed of a cruise ship is 50 km/hr. How far will the ship travel in 14 hours?
A car travels 240 kilometers in 3 hours. What is the speed of the car during that time? Step 1: Speed = Distance/Time Step 2: Speed = 240 km/3hrs Step 3: Speed = 80 km/hr Answer: The speed of the car is 80 km/hr.
The speed of a cruise ship is 50 km/hr. How far will the ship travel in 14 hours? Step 1: Speed = Distance/Time Step 2: Speed = 50km/hr Step 3:50 km x 14 hrs = 700km/14 hrs Answer: The ship will travel 700 km in 14 hrs.
Measuring Motion The speed of a moving object is not always constant. For example, a cyclist takes a long bike ride. She begins slowly for the first two hours and picks up speed for the third hour. After three hours, she takes a break before finishing the final two hours of her ride.
Measuring Motion Clearly, her speed changes many times throughout her journey. Dividing the total distance by the total time does not tell you her speed for every point of her journey. Instead it gives you her average speed. In fact, the formula you just learned for calculating speed – distance/time – always gives you the average speed.
Velocity Velocity: speed in a given direction Example: Suppose a runner moves eastward at 10 m/sec His speed is 10 m/sec His velocity is 10 m/sec east
Velocity Combining Velocities Suppose you are rowing a boat downstream at 16 km/hr. Would it surprise you to learn that you are actually going faster than 16 km/hr? How is this possible?
Measuring Motion The river is also moving, say at 10 km/hr. Since you are rowing downstream, you are going in the same direction as the river. The two velocities combine. So you are moving at 26 km/hr. *Velocities that have the same direction are added together.
Measuring Motion If you were rowing 16 km/hr upstream, you would be going 16 km/hr – 10 km/hr, or 6 km/hr. * Velocities that have opposite directions are subtracted from each other.
Frame of Reference Frame of Reference: the background or point that is assumed to be stationary and is used for comparison when motion is described Depends on the type of movement and the position which you are observing from Most common frame of reference: the Earth
Frame of Reference sim/mfm05_pg7_relmotion/mfm05_pg7_relmotion.html