Physics Lecture: Motion and Acceleration

Flashcards covering Galileo's inclined plane experiments, the concept and calculation of acceleration, free fall, and idealized physical cases.

What formula expresses the velocity acquired by an object starting from rest undergoing constant acceleration?

$$\text{Velocity acquired} = \text{acceleration} \times \text{time}$$

What is the definition and mathematical expression for average acceleration?

$$\text{Acceleration} = \frac{\text{change of velocity}}{\text{time interval}} = \frac{\Delta v}{\Delta t}$$

What did Galileo discover about falling objects when air resistance is small enough to be ignored?

All objects fall with the same unchanging acceleration, regardless of their weight or size.

Why did Galileo use inclined planes to study falling objects?

Lacking accurate timing devices, he used inclined planes effectively to slow down accelerated motion so he could investigate it more carefully.

Why do physicists study idealized cases that strip away real-world factors like friction and air resistance?

Real situations involve multiple orders of effects; stripping a situation to its basic first-order effect allows for clear understanding before examining secondary effects.

In what three ways can an object's velocity be changed to cause acceleration?

By changing its speed, changing its direction, or changing both its speed and its direction.

Why does a unit for time enter twice in the unit for acceleration?

Time enters once for the unit of velocity and a second time for the time interval in which the velocity is changing.

What is the acceleration of a car that goes from rest to $90\,\text{km/h}$ in $10\,\text{s}$?

$$9\,\text{km/h}\cdot\text{s}$$

If an airplane speeds up from $0$ to $5\,\text{km/h}$ in $10\,\text{s}$ and a skateboard does so in $1\,\text{s}$, what are their respective accelerations?

The airplane's acceleration is $0.5\,\text{km/h}\cdot\text{s}$ and the skateboard's acceleration is $5\,\text{km/h}\cdot\text{s}$.

If a car increases speed from $60\,\text{km/h}$ to $65\,\text{km/h}$ in $2.5\,\text{s}$ while a bicycle goes from rest to $5\,\text{km/h}$ in $2.5\,\text{s}$, which has the greater acceleration?

Both undergo the exact same acceleration of $2\,\text{km/h}\cdot\text{s}$.

How do the velocities of two cars compare if they move at the same speed but in opposite directions?

They have opposite velocities because velocity accounts for both speed and direction.

When does a rolling ball on an incline achieve its maximum acceleration?

When the incline is tipped vertically, causing it to fall with the acceleration of a free-falling object.