vectors review

A quantity with a magnitude and direction is called a

Answer explanation

vectors have magnitude and direction

Which of the following quantities is a vector?

• time

• mass

• temperature

• acceleration

Answer explanation

Time, mass, and temperature do NOT have direction. Acceleration has direction, so it is a vector.

Which of the following quantities is NOT a vector?

• speed

• velocity

• displacement

• acceleration

Answer explanation

Velocity has direction.

Speed does not have direction, so speed is scalar.

A plane is flying 100 mi/hr North and it encounters a wind blowing 30 mi/hr South. What is the resultant velocity of the plane?

• 70 mi/hr South

• 70 mi/hr North

• 130 mi/hr South

• 130 mi/hr North

Answer explanation

Draw this out.

100 mi/hr North minus 30 mi/hr South =

70 mi/hr North

A vector is drawn so that 100 mi/hr is 5 cm long. How long would you draw a 50 mi/hr vector with the same scale?

• 2.5 cm

• 5 cm

• 7.5 cm

• 10 cm

Answer explanation

the scale would be

1 cm = 20 mi/hr

so a 50 mi/hr vector would be 2.5 cm long

(50 is half of 100, so the length would be half as well)

When drawing velocity, the arrow shows the direction.

• True

• False

Answer explanation

The arrow shows the direction the vector is pointing

When drawing velocity, the length of the arrow shows the direction.

• True

• False

Answer explanation

The arrow shows the direction the vector is pointing.

The length of the vector shows the size (the magnitude).

What is the resultant velocity of the baseball shown here?

• 10 m/s

• 70 m/s

• 50 m/s

• 120 m/s

Answer explanation

These vectors make a triangle. This is solved using Pythagorean theorem.

What is the direction of the resultant velocity of the baseball shown here?

• down to the right

• up to the left

• up to the right

• down to the left

Answer explanation

The resultant velocity points from start to finish.

If one vector is pointing to the right, and the other vector is pointing down, the resultant vector points down to the right.

A vector is drawn so that 100 mi/hr is 5 cm long. How long would you draw a 200 mi/hr vector with the same scale?

• 2.5 cm

• 5 cm

• 7.5 cm

• 10 cm

Answer explanation

the scale would be

1 cm = 20 mi/hr

so a 200 mi/hr vector would be 10 cm long

(200 is 2x bigger than 100, so the length would be 2x as long)