Exploring Creation Physical Science Module 9 – Flashcards
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Define: reference point
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A point against which position is measured.
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Define: vector quantity.
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A physical measurement that contains directional information.
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Define: scalar quantity
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A physical measurement that does not contain directional information.
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Define: acceleration
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The time rate of change of an object's velocity.
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Define: free fall
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The motion of an object when it is falling solely under the influence of gravity.
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Why do you need a reference point to determine if an object is in motion or not?
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In order for motion to occur, an object's position must change which needs a reference point to determine. The reference point allows you to determine whether or not position changes.
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You and your friend are on a bicycle together. As you ride along you pass a dog barking. Who/what is in motion relative to you?
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the dog
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Same scenario - who/what is not in motion relative to you?
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your friend
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How many miles per hour does a train travel if it makes a 50 mile trip in 30 minutes?
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The formula is distance/time but the minutes needs to be changed to hours. 30 minutes = .5 hours. So it would be 50 miles/.5 hrs = 100 m/hr
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What is the velocity of a tricycle (in meters per second) if it travels 2 km west in 8 minutes?
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First the units need to be the same so the km needs to be changed to meters and the minutes changed to seconds. 2 km *1000m/1km = 2000 m 8 minutes * 60 seconds/1 min = 480 seconds Velocity = distance/time = 2000 m/480 sec. = 4.17 m/sec west
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What physical quantity is being measured: a. 6 miles per minute west b. 50 yards c.14 millimeters per hour to the south d. 15 meters per second
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a. acceleration b.distance c. velocity d. speed
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A boy throws a ball which has a velocity of 10 meters per second east. His dog chases the ball running at 12 meters per second. What is the relative velocity.
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Since they are both going the same direction, the velocities are subtracted from each other. The relative velocity is 12 - 10 m/sec east = 2 m/sec east toward each other. If the ball was faster than the dog than if would read " away from each other".
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If a car is traveling constantly to the east at 50 m/hr for 30 minutes, what is its acceleration during that time?
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Since the velocity is constant, there is no change, so the acceleration is zero.
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A ball rolls down a hill with a velocity of 5 meters per second south. If the ball comes to a complete stop in 10 seconds, what was its acceleration.
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A = (final velocity - initial velocity)/time A = (0-5) m/sec/10 sec. A = -0.5 m/sec south A = 0.5 m/sec north (remove the negative and write the opposite direction
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A train goes from 0 to 50 miles per hour east in 10 seconds. What is its acceleration?
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First the seconds have to be converted to hours: 10 seconds.* 1 hour/60 min * 1min/60 sec. = .0028 hour A = (final velocity - initial velocity)/time A = (5 - 0) mi/hr./ .0028 hr. A = 1,785.7 mi/hr east
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A girl standing on the Empire State Building throws a rock down toward the ground with one and drops a ball at the same time with the other. After both leave her hands, does one have a greater acceleration? If so, which one?
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Neither has greater acceleration. Both objects are falling near the surface of the earth; thus, they are each in free fall. That means they both have equal acceleration. The ball was given more initial velocity, so it will trvel faster. The acceleration on both is the same, however (9.8 m/sec or 32 ft/sec).
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If a feather and a baseball were dropped from a tall building at the same time, the baseball would hit the ground first. Why?
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The feather is more affected by air resistance than the rock.
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A scientist drops a piece of clay from the top of his 3 story building and measures the time it takes to hit the ground (2 seconds). How tall is the building in feet?
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Distance = 1/2 * acceleration * time Distance = 1/2 * (32 ft/sec) * (2 sec) * (2 sec) Distance = 64 ft
