Question

One dimensional motion describes the changes in the position of
an object over time in terms of its displacement, velocity, and
acceleration *in one direction*. The motion in that
direction is independent of the displacement, velocity, and
acceleration associated with any of the perpendicular directions.
For example, the acceleration due to gravity near the surface of
the earth has a value of 9.8 m/s^{2}, downward. This
affects the vertical motion of an object but has no effect on the
motion of the object in either of the horizontal directions. Thus,
one-dimensional motion forms the foundation of our understanding of
general motion in three dimensions.

**Instructions for this activity:**

For our discussion, you will address one of three slightly different versions of the case of a ball falling to the base of a 50.0 m tall building.

- Neglect air resistance.
- The magnitude of the acceleration is 9.80 m/s
^{2}. - The eventual position of the ball is at the base of the building, 50.0 m below this initial position.
- Upward is defined as positive. Displacements, velocities and
accelerations directed upwards are positive. Conversely, if
directed downwards, these same quantities are negative. Thus, the
base of the building is located at -50.0 m, and acceleration is
-9.80 m/s
^{2}.

For the Case you are assigned, answer the following questions. Support your answer with any necessary calculations.

- How long does the ball take to reach the base of the building?
- What is the final velocity of the ball just before striking the ground?
- Answer the additional questions for your Case as specified in the table below.

Freefall Case 1: Near the edge of the building the ball is thrown upward with an initial velocity of 14.7 m/s, at time t = 0.00 s.

Additional question: If downward were to have been chosen as the positive direction, how would this affect the values of displacement, velocity, and acceleration given in the description of the case study? Comment on the dependence of physical results, if any, on the choice of the positive direction chosen by observers.

Answer #1

1- A student standing on top of a 170-m high building threw a
stone upward with an initial velocity of 40 m/s. Assume that
g=-9.80 m/s2. Upward direction is positive and downward is
negative.
What is the vertical location of the stone in meters, with
respect to the top of the building, after 11.0 seconds? (hint: pay
attention to the sign here!)
2- A student standing on top of a 50-m high building threw a
stone upward with an initial...

Q1)A student standing on top of a 160-m high building threw a
stone upward with an initial velocity of 45 m/s. Assume that
g=-9.80 m/s2. Upward direction is positive and downward is
negative.
What is the speed, in m/s, of the stone after 5.0 seconds?
(hint: speed is always positive!)
Your Answer:
Q2)
A student standing on top of a 150-m high building threw a stone
upward with an initial velocity of 44 m/s. Assume that g=-9.80
m/s2. Upward direction...

1. Over a time interval of 2.20 years, the velocity of a planet
orbiting a distant star reverses direction, changing from +23.7
km/s to -24.2 km/s. Find (a) the total change in
the planet's velocity (in m/s) and (b) its average
acceleration (in m/s2) during this interval. Include the
correct algebraic sign with your answers to convey the directions
of the velocity and the acceleration.
2. A car is traveling at a constant speed of 27.2 m/s
on a highway. At...

A small object with mass 4.10 kg moves counterclockwise with
constant speed 1.35 rad/s in a circle of radius 3.05 m centered at
the origin. It starts at the point with position vector
3.05î m. Then it undergoes an angular displacement
of 8.65 rad.
(a) What is its new position vector?
m
(b) In what quadrant is the particle located and what angle does
its position vector make with the positive x-axis?
Second at ??°
(c) What is its velocity?
m/s...

One end of a cord is fixed and a small 0.550-kg object is
attached to the other end, where it swings in a section of a
vertical circle of radius 2.50 m, as shown in the figure below.
When
θ = 18.0°,
the speed of the object is 6.50 m/s.
An object is swinging to the right and upward from the end of a
cord attached to a horizontal surface. The cord makes an angle
θ with the vertical. An...

One end of a cord is fixed and a small 0.250-kg object is
attached to the other end, where it swings in a section of a
vertical circle of radius 1.00 m, as shown in the figure below.
When
θ = 22.0°,
the speed of the object is 8.50 m/s.
An object is swinging to the right and upward from the end of a
cord attached to a horizontal surface. The cord makes an angle
θ with the vertical. An...

Question 1
The study of Uniform Circular Motion relates to objects
traveling with constant speed around a circle with radius, R. Since
the object has a constant speed along a circular path, we can also
say that
A)
the object has zero velocity.
B)
the object has a constant acceleration magnitude.
C)
the object has zero acceleration.
D)
the object has a constant velocity.
E)
the object has an increasing acceleration.
Question 2
Uniform Circular Motion (UCM) problems are just...

1. A body is launched upward at 30 m/s. After how much time is
the object moving with half the initial speed, but in the downward
direction to the nearest hundredth of a second?
2. A girl launches a ball straight up into the air on Earth. The
average velocity of the ball from launch point until it attains its
maximum height is 24 m/s. Ignore air resistance.
What is the maximum height above the launch point to the nearest...

1. For a stationary ball of mass m = 0.200 kg hanging from a
massless string, draw arrows (click on the “Shapes” tab) showing
the forces acting on the ball (lengths can be arbitrary, but get
the relative lengths of each force roughly correct). For this case
of zero acceleration, use Newton’s 2nd law to find the
magnitude of the tension force in the string, in units of Newtons.
Since we will be considering motion in the horizontal xy plane,...

For Each Question:
- Mark As True or False
- Give Reason
- Prove Your Answer By An Example
1. The magnitude of the average velocity is not the average
speed.
2. The magnitude of the instantaneous velocity is the
instantaneous speed.
3. The word deceleration means always slowing down.
4. The acceleration of a projectile at the top of its
trajectory is zero. While the velocity at the top of the motion of
an object thrown upward momentarily goes...

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