Motion Test

If the students continue at the same speed, which statement describes the total distance traveled after 90 seconds?

• Student 1 traveled 40m and student 2 traveled 20m

• Student 1 traveled 20m and student 2 traveled 40m

• Student 1 traveled 60m and student 2 traveled 30m

• Student 1 traveled 70m and student 2 traveled 25m

Answer explanation

To find the distance at 90 seconds for both students, you will need to calculate the speed of both students. Speed= distance/time. Student 1 had a speed of 0.67 m/s while student 2 had a speed of 0.33 m/s. The equation for distance is: d=s x t.

Student 1: 0.67 m/s x 90s= 60m

Student 2: 0.33 m/s x 90s= 30m

Tags

NGSS.MS-PS3-1

A person swims three lengths of the pool: from point X to point Y, from point Y to point X, and then from point X to point Y again.

​Which table shows the magnitudes of the distance the person traveled and the person’s final displacement?

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Answer explanation

Distance is the total amount of motion traveled.

Displacement is the straight line distance between the starting point and the ending point.

Because the swimmer swam 3 lengths of a 50m pool, their distance is = 50 + 50 + 50= 150m

Because the swimmer ends at point Y, which is 50 m away from point X, the displacement is 50 m.

The displacement of the student from start to finish is...

• 1.40 km North

• 1.40 km South

• 5.0 km North

• 5.0 km South

Answer explanation

The displacement is the straight line distance between the starting point and the ending point. So, you must add the two straight line distances between these two points. 0.60 km and 0.80 km.

Displacement is also a vector quantity, meaning that it shows magnitude AND direction. The ending point is south of the starting point. Therefore, the answer is 1.40 km south.

An object is moving west at 30 km/h and another object is moving north at 30 km/h.
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​Which of the following statements describes the motion of both objects?

• They have the same speed and same velocity

• They have different speeds and different velocities

• They have different speeds but the same velocity

• They have the same speed but different velocities.

Answer explanation

Remember, velocity is a vector quantity. Meaning, that it shows speed AND direction. Both of the objects had the same speed. The only difference is that they are going in two different directions, making their velocities different.

Which table describes the object’s motion?

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Answer explanation

This is a SPEED vs TIME graph!

A straight diagonal line going upwards represents acceleration (speeding up)

A flat horizontal line represents constant speed

A straight diagonal line going downwards represents deceleration (slowing down)

Tags

NGSS.MS-PS2-2

NGSS.MS-PS3-1

A car initially traveling at 8.0 meters per second doubles its speed while traveling in a northeast direction.

Students used a table to record the initial and final conditions for speed and velocity. Which table is correct?

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Answer explanation

Speed is a scalar quantity. Meaning that it will only show magnitude. The unit for speed is m/s.

Velocity is a vector quantity, meaning that it shows magnitude and direction. So the unit for velocity is m/s and direction (mph north)

Tags

NGSS.MS-PS2-1

NGSS.MS-PS2-2

What is the student's speed once they had reached 100 meters?

• 0.3 m/s

• 3.33 m/s

• 300 m/s

• 3,000 m/s

Answer explanation

Speed = Distance/Time

Distance= 100 m

Time= 30s

100/30= 3.33 m/s

Tags

NGSS.MS-PS3-1

During an investigation, a student measured the distances that four electric toy cars traveled in 12 seconds.
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Which toy car had an average speed of 2.5 m/s?

• Car 1

• Car 2

• Car 3

• Car 4

Answer explanation

Speed= Distance/Time

Car three had a distance of 30m and the time it took to travel those 30 meters was 12 seconds.

Speed= 30m/12s= 2.5 m/s

Tags

NGSS.MS-PS3-1

Which of the following graphs best represents the speed of the person on the sled from the top of the hill to the mat?

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Answer explanation

As the sled goes down the hill, the speed of the sled increases (accelerates). Once it reaches the bottom of the hill, the sled begins to move at a constant speed for a certain period of time. Then, the sled begins to slow down and comes to a stop. (decelerates)

Acceleration on a speed vs time graph is a straight diagonal line trending upwards.

Constant speed on a speed vs time graph is a flat horizontal line.

Deceleration on a speed vs time graph is a straight diagonal line trending downwards.

Tags

NGSS.MS-PS3-1

Which of the following setups would cause the ball to roll with the motion shown in the graph?

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Answer explanation

According the speed vs time graph, the object is increasing its speed and then remains constant for the duration of the time.

So, the graph that has the ball rolling down the ramp and continues on the flat table top represents an object increasing speed and then continuing at a constant speed.

Tags

NGSS.MS-PS2-2

NGSS.MS-PS3-1

NGSS.MS-PS3-5