2D Kinematics

Question 1

What is vector?

Answer 1

A variable that has both a magnitude & direction

Question 2

How are vectors added (combined)?

Answer 2

By placing the tail of next vector onto the tip of the preceding vector.

Question 3

An apple is being held at rest in a car that is moving at 90 km/h west. How fast is the apple moving?

Answer 3

It depends on the frame of reference. It could be 0 km/h relative to the car. It could be 90 km/h west relative to the ground. Or it could be something else completely if the frame of reference is moving relative to the ground.

Question 4

What is the acceleration of an object with an initial velocity of 5m/s East, and a final velocity of 5m/s North, over a time of 7 seconds?

Answer 4

1 m/s/s NW

Question 5

What does it mean to RESOLVE a vector?

Answer 5

It means you need to separate the vector into its individual dimension vectors. If the vector is 2D then you will separate the original vector into two individual perpendicular vectors.

Question 6

What is the southern vector component of a velocity of 40m/s East 30degrees South?

Answer 6

20m/s south

Question 7

What is the direction of the resultant vector that has a 30.0 m West, and 40.0 m North components?

Answer 7

East 53.1 degrees North

Question 8

What is projectile motion?

Answer 8

Objects that move freely under the influence of gravity alone.

Question 9

What is a trajectory?

Answer 9

The path traveled by the projectile

Question 10

The shape of a trajectory can be described as a…?

Answer 10

Parabola.

Question 11

What is the range of a projectile?

Answer 11

The maximum distance the projectile can travel.

Question 12

What is true about the velocity of a projectile at maximum height?

Answer 12

Its vertical velocity is ZERO, while maintaining its original horizontal velocity.

Question 13

If the barrel of gun is aimed directly at a monkey hanging in a tree, should the monkey stay, or drop out of the tree, when the trigger is pulled?

Answer 13

The monkey should stay. If the monkey drops, the bullet will hit where it was initially aimed, because both the bullet and the monkey fall at the same rate.

Question 14

What is the best angle to fire a projectile for maximum range, off of level ground?

Answer 14

45 degrees

Question 15

What is the best angle to fire a projectile for maximum range, off of a cliff?

Answer 15

Significantly less than 45 degrees

Question 16

How do the sight line of a scope, and the sight line of the barrel of a rifle compare?

Answer 16

The sight line of the scope will be BELOW that of the sight line of the rifle

Question 17

If a ball is kicked off of level ground, and takes 0.60 seconds to reach its maximum height, how long would it take to land?

Answer 17

The total time in the air would be 1.20 seconds (place value)

Question 18

A kid aims a slingshot directly at a squirrel sitting on a fence. If the rock from a slingshot takes 1.0 seconds to reach the fence, and given the squirrel drops himself off of the fence the instant the rock was fired, how fast would the squirrel be travelling at the time it got hit?

Answer 18

9.81m/s downward

Question 19

A ball is thrown with a velocity of 8 m/s forward, and 3 m/s upward. What is the balls total velocity at its maximum height?

Answer 19

8 m/s forward

Question 20

At what point(s) in a level ground projectile’s path is its velocity at a maximum?

Answer 20

at the start and end of its motion. Vi and Vf, both of which are the same

Question 21

If a ball is kicked at an angle of 25 degrees above the horizon off of level ground, what other angle could another similar ball be kicked so that it lands in the same place?

Answer 21

65 degrees

Question 22

If a ball is kicked at an angle of 25 degrees above the horizon off of a cliff, what other angle could another similar ball be kicked so that it lands in the same place?

Answer 22

It all depends. Not enough information given.

Question 23

If a gun is aimed horizontally, and a stone drops at the same instant the gun is fired, what would hit the ground fired first? (assume no air resistance)

Answer 23

The stone and bullet will land at the same time.

Question 24

What does it mean to do a UV check?

Answer 24

Make sure all the units of similar quantities are the same, (everything is in meters, seconds, grams, ect.) [Not Km/h and m/s] Make sure all the vectors are aligned in the same direction.

Question 25

True or False +9.81 m/s/s downward is the same -9.81 m/s/s upward.

Answer 25

True

Question 26

A ball is kicked off of level ground, and reaches a range of 18m in a time of 3.0 seconds. What is the balls vertical displacement from its initial position upon landing?

Answer 26

Zero. 0.0m It starts and ends at the SAME vertical position. :)

Question 27

What is a different way of expressing the direction North 30 degrees East?

Answer 27

East 60 degrees North

Question 28

A small airplane has an air velocity of 30.0 m/s North 20 degrees East, and is flying in air that moving at 40.0 m/s West 20 degrees North. What is the airplane’s velocity relative to the ground?

Answer 28

50.0 m/s. Because the two vectors are perpendicular (90degrees), and because it is clearly a 3,4,5 type triangle, the number can be determined without any math. :)

Question 29

If you know the initial velocity, final velocity, and the displacement, what formula would you use to find the time?

Answer 29

t=2d/(vi+vf)

Question 30

If a golf ball is hit off the ground at 79 m/s Right 30 degrees Up, what will it’s velocity be if it lands on level ground a quarter of a second later, what would its final landing velocity be.

Answer 30

Using symmetry (no math :) ) we can see that it would have to be 79 m/s Right 30 degrees Down.