Physics Section 3: Falling Objects and Motion

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Questions and Answers

How would the trajectory of the stunt dummy appear to an observer on the ground?

A zigzag motion

A parabolic projectile path (correct)

A straight line toward the airplane

A curved line upward

What components of motion does the stunt dummy exhibit after being dropped from the airplane?

Only horizontal component of velocity

Only vertical component of velocity

No velocity components

Vertical and horizontal components of velocity (correct)

If a baseball is thrown opposite to the motion of a train, how do you calculate its velocity relative to Earth?

Add the speed of the train and the baseball's speed

Ignore the train's speed and use only the baseball's speed

Multiply the speed of the train by the speed of the baseball

Subtract the baseball's speed from the speed of the train (correct)

In a vacuum, what would be the behavior of a freely falling object compared to an object moving horizontally?

Both motions will be unaffected by air resistance Signup and view all the answers

What happens to the velocity of an object in free fall over time?

The velocity increases due to acceleration Signup and view all the answers

What would be the effect of air resistance on the stunt dummy's trajectory?

It would create a longer time to reach the ground Signup and view all the answers

Which scenario best illustrates positive velocity with negative acceleration?

An object moving upward while slowing down Signup and view all the answers

If two observers describe the same object's motion, they might not agree on several features. Why is this?

They are in different frames of reference Signup and view all the answers

What is the velocity of the ball at the peak of its upward motion?

0 m/s Signup and view all the answers

What is the value of the acceleration of the ball during its entire motion?

−9.81 m/s² Signup and view all the answers

How does the slope of the velocity-time graph relate to the acceleration of the ball?

The slope is constant. Signup and view all the answers

What happens to the ball's velocity immediately after it reaches 0 m/s at the peak?

It begins to decrease further into negative values. Signup and view all the answers

Which of the following best describes free fall motion?

Motion solely under the influence of gravity. Signup and view all the answers

In the context of the ball's motion, what does a negative acceleration indicate?

The ball's velocity is decreasing. Signup and view all the answers

During which part of its motion is the ball's velocity actually 0 m/s?

At the peak of its trajectory. Signup and view all the answers

What is the relationship between upward motion and acceleration in free fall?

Acceleration remains constant even during upward motion. Signup and view all the answers

What happens to the velocity of an object thrown upward as it rises?

It decreases steadily. Signup and view all the answers

What is the acceleration of an object in free fall, regardless of its direction of motion?

-9.81 m/s² Signup and view all the answers

At the peak of its path, what is the velocity of an object thrown upward?

Zero. Signup and view all the answers

When an object in free fall has negative velocity, what does that imply about its motion?

It is speeding up. Signup and view all the answers

How can the motion of an object be described when it is moving upward with a positive velocity while experiencing negative acceleration?

The object is decelerating upwards. Signup and view all the answers

What occurs to the position of an object experiencing a downward acceleration while moving upward?

The position increases at a decreasing rate. Signup and view all the answers

Which of the following accurately describes the motion of an object right before it reaches its peak height?

Velocity is zero, acceleration is negative. Signup and view all the answers

If an object is thrown upwards with an initial velocity, when does it experience the maximum negative acceleration?

At the peak height. Signup and view all the answers

Study Notes

Section 3: Falling Objects

Freely falling bodies experience constant acceleration due to gravity
Objects of different masses fall at the same rate in a vacuum
Free fall acceleration (g) is approximately 9.81 m/s² on Earth

Free Fall

Free fall occurs when only gravity acts on an object
Displacement increases with each time interval
Velocity increases by a constant amount in each time interval

Acceleration is constant during upward and downward motion

Objects thrown upwards experience constant downward acceleration
Velocity is zero at the peak of the upward motion
Acceleration remains constant throughout the motion

Vectors indicate direction; scalars do not

Scalars have magnitude only (e.g., speed, volume)
Vectors have both magnitude and direction (e.g., velocity, displacement)

Vectors can be added graphically

Vectors can be added by placing the tail of one vector at the head of another
The resultant vector is drawn from the tail of the first vector to the head of the last.
Magnitude measured with a ruler, direction measured with a protractor

Properties of Vectors

When vectors act at the same point, a resultant vector can be found
Vectors can be moved parallel to themselves in diagrams
Vectors can be added in any order

Multiplying or dividing vectors by scalars results in vectors

Multiplying a vector by a scalar changes the magnitude but not the direction
Multiplying a vector by a NEGATIVE scalar reverses the direction

Section Review

Review of scalar and vector quantities
Examples of quantities in a given situation

Projectile Motion

Projectiles follow parabolic paths
Projectile motion is free fall with an initial horizontal velocity
Horizontal velocity remains constant during projectile motion
Vertical motion is affected by gravity

Vertical Motion of a Projectile that Falls from Rest

Equations relate vertical velocity, acceleration, and displacement

Projectiles Launched Horizontally

Constant horizontal velocity during projectile motion
Vertical displacement due to constant acceleration due to gravity

Projectiles Launched at an Angle

Initial velocity has horizontal and vertical components
Horizontal motion analyzed using horizontal components
Vertical motion analyzed using vertical components

Relative Motion

Velocity measurements differ in frames of references
Observers in different frames will measure different displacements (distances) and velocities of objects

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Description

This quiz covers essential concepts in physics related to falling objects and motion, focusing on the effects of gravity and how it influences both upward and downward movement. You'll also learn about the distinction between scalars and vectors, including their properties and how they can be added together. Test your understanding of free fall and the kinematic principles involved.