# Vector/Relative Motion Questions

• zak.hja
In summary, the boy rides his bicycle at a velocity of 0.50 m/s [N] and throws a ball to his friend, who is 5.0m east of his position. The boy can throw the ball at a maximum velocity of 2.0m/s and must throw it in a direction that cancels out all the unwanted directions for it to reach his friend. The horizontal velocity will be 2.0 m/s and the boy will adjust the vertical velocity to suit, accounting for gravity.
zak.hja

## Homework Statement

A boy rides his bicycle down the sidewalk at a velocity of 0.50 m/s [N]. As he passes his friend, who is 5.0m east of his position, he throws a ball to him.

a) If he can throw the ball at a maximum velocity of 2.0m/s, in which direction must he throw it in order for it to reach his friend?

b)How long does it take the ball to reach his friend?

c^2=a^2+b^2

## The Attempt at a Solution

Well, I know that a right triangle can be formed with the vectors. We've just started this topic today, so I'm a bit unsure of where to put the numbers. One side of the triangle will be 0.5 m/s in magnitude, and another will be 2.0 m/s. How would this triangle look?

Any assistance is appreciated; thank you :)

Do you know how to do it if the target is moving?

You need to think through the physics without worrying, right away, about the "right way" to do this thing.

Without air resistance[*], if the bio just let go of the ball, what speed and direction would it travel? How fast?
You need the ball to go directly in what direction?

So the direction you throw it must cancel out all the directions you don't want it to go in.

------------------------------

[*] or gravity apparently - we'll treat the 2.0m/s as the horizontal velocity, the boy adjusts the vertical velocity to suit. (You'll probably do projectile motion later.)

## 1. What is vector motion?

Vector motion refers to the movement of an object in a specific direction with a specific magnitude. It involves both the speed and direction of the object's movement.

## 2. What is relative motion?

Relative motion refers to the motion of an object in relation to another object. It takes into consideration the position, speed, and direction of both objects.

## 3. How do you calculate relative velocity?

Relative velocity can be calculated by subtracting the velocities of the two objects in relation to a fixed point or frame of reference. This can be done using vector addition or subtraction.

## 4. What is the difference between speed and velocity?

Speed is a scalar quantity that only indicates how fast an object is moving, while velocity is a vector quantity that describes the speed and direction of an object's motion.

## 5. How does the concept of frame of reference apply to vector/relative motion?

A frame of reference is a set of coordinate axes used to describe the position and motion of an object. When dealing with vector/relative motion, it is important to establish a consistent frame of reference for accurate calculations and comparisons between objects.

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