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Questions and Answers
What characterizes a freely falling object?
What characterizes a freely falling object?
- It moves solely under the influence of gravity. (correct)
- It experiences constant velocity.
- It must be initially at rest.
- It is only influenced by air resistance.
The acceleration of an object in free fall on Earth is constant and approximately equal to 9.8 m/s², regardless of the object's mass.
The acceleration of an object in free fall on Earth is constant and approximately equal to 9.8 m/s², regardless of the object's mass.
True (A)
If an object is thrown upwards, what is its velocity ($v$) at its maximum height? Assume only gravity ($g$) is acting on it.
If an object is thrown upwards, what is its velocity ($v$) at its maximum height? Assume only gravity ($g$) is acting on it.
0
When calculating the distance an object falls freely from rest under gravity ($g$) for time $t$, the formula is $distance = ______$.
When calculating the distance an object falls freely from rest under gravity ($g$) for time $t$, the formula is $distance = ______$.
In free fall, what is the relationship between the time it takes for an object to reach its maximum height when thrown upwards and the time it takes to fall back down to its initial position?
In free fall, what is the relationship between the time it takes for an object to reach its maximum height when thrown upwards and the time it takes to fall back down to its initial position?
Match the description with the appropriate kinematic equation for free fall:
Match the description with the appropriate kinematic equation for free fall:
A stone is dropped into a well. The sound of the splash is heard 3 seconds later. Assuming constant gravitational acceleration and neglecting air resistance, what additional information would be needed to calculate the exact depth of the well?
A stone is dropped into a well. The sound of the splash is heard 3 seconds later. Assuming constant gravitational acceleration and neglecting air resistance, what additional information would be needed to calculate the exact depth of the well?
A basketball player jumps vertically with an initial upward velocity of 4 m/s. Calculate to two decimal places the total time in seconds that the player spends in the air.
A basketball player jumps vertically with an initial upward velocity of 4 m/s. Calculate to two decimal places the total time in seconds that the player spends in the air.
If a ball is thrown upwards with an initial velocity of 15 m/s, the final velocity when it is caught by the person who threw it will be exactly -15 m/s, assuming negligible air resistance.
If a ball is thrown upwards with an initial velocity of 15 m/s, the final velocity when it is caught by the person who threw it will be exactly -15 m/s, assuming negligible air resistance.
A ball is thrown upwards with a speed of 15 m/s. Calculate the maximum height reached by the ball in meters. Choose the option that's accurate to two decimal places.
A ball is thrown upwards with a speed of 15 m/s. Calculate the maximum height reached by the ball in meters. Choose the option that's accurate to two decimal places.
Flashcards
Free Fall
Free Fall
Motion under the influence of gravity alone, regardless of initial motion.
Velocity in Free Fall
Velocity in Free Fall
v = u + gt, where v is final velocity, u is initial velocity, g is acceleration due to gravity, and t is time.
Displacement in Free Fall
Displacement in Free Fall
∆y = ut + (1/2)gt², where ∆y is the displacement, u is initial velocity, g is acceleration due to gravity, and t is time.
Velocity-Displacement Relation
Velocity-Displacement Relation
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Value of 'g'
Value of 'g'
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Study Notes
Motion Due to Gravity
- Freely falling objects are influenced by gravity alone, irrespective of initial motion, which includes objects thrown upward or downward & released from rest.
- For straight-line motion equations, constant acceleration is replaced by 'g', where g equals 9.8m/s².
- Equations include:
- 𝑣 = 𝑢 + 𝑔𝑡
- ∆𝑦 = 𝑢𝑡 + (1/2)𝑔𝑡²
- 𝑣² = 𝑢² + 2𝑔∆𝑦
Example 1
- A boy drops a stone into a well and hears the stone hit the water after 3.0 seconds; solving for the depth of the well gives:
- 𝑦 = (1/2)𝑔𝑡² = (1/2) × 9.81 × 3² = 44.15 m
Example 2
- A basketball player jumps for 0.80 seconds to grab a rebound and solving for the jump height, requires first solving for initial velocity:
- 𝑢 = 0 - (-9.81 m/s² × 0.40s) = 3.92 m/s
- ∆𝑦 = (3.92 m/s × 0.40s) + (1/2)(-9.81 m/s²)(0.40s)² ∆𝑦 = 0.78 m
Example 3
- A ball is thrown upwards at a speed of 15m/s and is caught again, and solving for the max height requires:
- ℎ = (𝑣² − 𝑢²)/2𝑔 = (0² − 15²)/(2 × (−9.81)) = 11.47 𝑚
- How long to reach max height requires:
- 𝑡 = −𝑢/𝑔 = 15𝑚/𝑠 / 9.81𝑚/𝑠² = 1.53 𝑠
- How fast before caught requires:
- 𝑣 = 𝑔𝑡 = 9.81 × 1.53 = 15.0093
- How long the ball is in the air:
- total time = 2𝑡 = 2 × 1.53 = 3.06𝑠
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