Unit 5.1 and 5.2 | ES II |Motion Maps and Position - Time Graphs

Which object(s) gained speed?

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Answer explanation

In a motion map the arrows represent how fast an object is moving and indicate which direction the object is moving. In the picture, the arrows gradually become longer and the dots are farther apart, therefore we can determine that the object's speed is increasing.

Tags

NGSS.MS-PS3-1

NGSS.MS-PS2-2

NGSS.MS-PS3-5

Select all diagrams for which speed is constant.

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Answer explanation

In a motion map the arrows represent how fast an object is moving. If the length of the arrows remain constant, that means the object maintains a constant speed. An object at rest that never moves has a constant speed of 0 m/s.

Tags

NGSS.MS-PS3-1

Choose the Motion Map that represents the following:

An athlete is working out. They jog backwards slowly, pause, and then sprint quickly forward.

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Answer explanation

The athlete heads to the left originally, and the arrows are short indicating the athlete is jogging. The athlete then turns around and goes in the opposite direction, the arrows become longer to indicate the athlete is now sprinting.

Tags

NGSS.MS-PS3-1

NGSS.MS-PS2-2

NGSS.MS-PS3-5

NGSS.MS-PS2-1

Which object(s) is(are) maintaining a steady state of motion?

• A

• B

• C

• D

• E

Answer explanation

In a position vs time graph, if the motion of an object is represented by a straight line, that means the object is moving at a constant velocity. Objects A and E do not change position (horizontal lines), which means they both maintained a steady velocity of 0.

Which object(s) is(are) moving in the negative direction (to the left)?

• A

• B

• C

• D

• E

Answer explanation

Line D has a negative slope. The slope of position vs time graphs represent velocity. The sign of velocity indicates direction. Therefore, because D has a negative slope it indicates the object is moving in the negative direction.

Tags

NGSS.MS-PS3-1

Which object(s) is(are) not moving?

• A

• B

• C

• D

• E

Answer explanation

The motion of objects A and E are represented by horizontal straight lines. This means they never change their position. Another way to think about this, is they never change position along the y-axis, and the y-axis represents position.

We can determine that the velocity of C is changing because...

• It has a positive slope

• It has a negative slope

• It is curved which means the slope is changing

• It's slope goes from positive to negative

• The velocity of C is not changing

Answer explanation

The slope in a position vs. time graph represents the velocity of the object. If a line is straight, that means it's slope is constant. C is a curved lined, which means it's slope is changing. Therefore, it's velocity is changing.

Tags

NGSS.MS-PS3-1

We know that objects B and D change direction because...

• They are straight lines

• They cross the x-axis

• Neither object changes direction

Answer explanation

In a position-time graph, the velocity is represented by the slope of the line, and the sign of the velocity indicates direction. Because none of the lines changes from a positive to a negative velocity, none of the objects changed direction.

Which object(s) is(are) stationary at some point?

• A

• B

• C

• None

Answer explanation

B is stationary when it is a horizontal line.

Which objects start in the same position?

• A

• B

• C

• None

Answer explanation

B and C start at the same y-axis value. The y-axis represents position.