11th Relative Motion Worksheet 2 | PDF | Trajectory | Motion (Physics) - Free Printable
Educational worksheet: 11th Relative Motion Worksheet 2 | PDF | Trajectory | Motion (Physics). Download and print for classroom or home learning activities.
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Step-by-step solution for: 11th Relative Motion Worksheet 2 | PDF | Trajectory | Motion (Physics)
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Show Answer Key & Explanations
Step-by-step solution for: 11th Relative Motion Worksheet 2 | PDF | Trajectory | Motion (Physics)
Here is the complete solution and explanation for Part 1: Conceptual Understanding and Comparisons of your Relative Motion Worksheet.
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Answer:
Relative motion refers to the motion of an object as observed from a particular frame of reference. It describes how the position, velocity, or acceleration of one object appears to change with respect to another object or observer. Since motion is not absolute but depends on the observer’s point of view, we say motion is “relative” — meaning it must be measured *relative to* something else.
> Example: If you’re sitting in a moving car, a tree outside appears to move backward relative to you — even though the tree is stationary relative to the ground.
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Answer:
A frame of reference is a coordinate system (with origin and axes) used to measure the position, velocity, and acceleration of objects. It includes an observer and a set of rulers and clocks to make measurements. Frames can be stationary (like the ground) or moving (like a car or train). In physics, we often distinguish between inertial frames (non-accelerating) and non-inertial frames (accelerating).
> Example: The Earth’s surface is approximately an inertial frame; a bus accelerating forward is a non-inertial frame.
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Answer:
An observer in their own frame of reference always imagines that they are at rest — that is, they assign themselves a velocity of zero relative to their own frame. All motion they observe is then measured *relative to themselves*.
> Example: If you’re sitting in a moving train, you feel like you’re not moving — so you assume your velocity is zero. You see trees outside moving backward — that’s their motion relative to you.
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#### a) Draw the trajectory of the coin from Tim’s frame of reference.
Answer (description since drawing isn’t possible here):
From Tim’s perspective (inside the bus), he and the coin are both moving forward with the same speed as the bus. When he tosses the coin straight up, it goes up and comes straight back down into his hand — because there’s no horizontal force acting on the coin (ignoring air resistance). So, the trajectory is a straight vertical line — up and down.
> Think: Like tossing a ball while standing still — it goes up and down vertically.
#### b) Draw the trajectory of the coin from Matthew’s frame of reference.
Answer (description):
Matthew sees the bus moving forward. When Tim tosses the coin, the coin already has the same forward horizontal velocity as the bus (and Tim). As it moves upward and downward under gravity, it continues moving forward at constant horizontal speed. So, the trajectory is a parabola — like a projectile launched horizontally.
> Think: Like throwing a ball sideways off a moving car — it follows a curved path through the air.
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#### a) Draw the trajectory of the bomb from Tara’s frame of reference.
Answer (description):
Tara is flying with the plane, which is moving forward at constant speed. When she drops the bomb, it has the same horizontal velocity as the plane. From her perspective, the bomb falls straight down — because she and the bomb are moving together horizontally. So, the trajectory is a straight vertical line downward.
> Think: Like dropping a package out of a helicopter hovering over a target — it falls straight down relative to the helicopter.
#### b) Draw the trajectory of the bomb from Annie’s frame of reference.
Answer (description):
Annie is on the ground, so she sees the plane moving forward. When the bomb is dropped, it retains the plane’s forward horizontal velocity and begins falling due to gravity. So, the trajectory is a parabolic arc, starting at the drop point and curving downward as it travels forward.
> Think: Like launching a cannonball horizontally — it follows a parabola.
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Answer:
The tool will land directly beneath where the sailor dropped it — assuming the ship is moving at constant speed (no acceleration) and ignoring air resistance.
Explanation:
When the sailor drops the tool, the tool already has the same horizontal velocity as the ship (because it was carried along with the ship). Once dropped, no horizontal forces act on it (air resistance ignored), so it maintains that horizontal velocity. Meanwhile, the ship continues moving forward at the same speed. Therefore, the tool and the ship move forward together — so the tool lands right below the drop point.
This illustrates the principle of inertia (Newton’s First Law): objects in motion stay in motion with the same speed and direction unless acted upon by an external force. Since the tool and the ship share the same horizontal motion, they remain aligned vertically.
> Historical note: This problem was used to argue against the idea that the Earth rotates — people thought if Earth rotated, a dropped object should land behind. But Galileo showed that objects inherit the motion of the Earth, just like the tool inherits the motion of the ship.
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✔ Summary Key Concepts:
- Motion is relative — always measured with respect to a frame.
- Observers in their own frame consider themselves at rest.
- Objects retain horizontal velocity when dropped (if no air resistance).
- Trajectories differ depending on the observer’s motion.
Let me know if you’d like diagrams sketched or explanations for Part 2!
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1) What is meant by relative motion?
Answer:
Relative motion refers to the motion of an object as observed from a particular frame of reference. It describes how the position, velocity, or acceleration of one object appears to change with respect to another object or observer. Since motion is not absolute but depends on the observer’s point of view, we say motion is “relative” — meaning it must be measured *relative to* something else.
> Example: If you’re sitting in a moving car, a tree outside appears to move backward relative to you — even though the tree is stationary relative to the ground.
---
2) What is a frame of reference?
Answer:
A frame of reference is a coordinate system (with origin and axes) used to measure the position, velocity, and acceleration of objects. It includes an observer and a set of rulers and clocks to make measurements. Frames can be stationary (like the ground) or moving (like a car or train). In physics, we often distinguish between inertial frames (non-accelerating) and non-inertial frames (accelerating).
> Example: The Earth’s surface is approximately an inertial frame; a bus accelerating forward is a non-inertial frame.
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3) When you are asked what the motion of an object is relative to a frame of reference, what velocity does an observer in that frame of reference imagine that s/he has?
Answer:
An observer in their own frame of reference always imagines that they are at rest — that is, they assign themselves a velocity of zero relative to their own frame. All motion they observe is then measured *relative to themselves*.
> Example: If you’re sitting in a moving train, you feel like you’re not moving — so you assume your velocity is zero. You see trees outside moving backward — that’s their motion relative to you.
---
4) Tim is walking down the aisle of a speeding bus and tosses a coin into the air. Matthew is standing on the sidewalk outside.
#### a) Draw the trajectory of the coin from Tim’s frame of reference.
Answer (description since drawing isn’t possible here):
From Tim’s perspective (inside the bus), he and the coin are both moving forward with the same speed as the bus. When he tosses the coin straight up, it goes up and comes straight back down into his hand — because there’s no horizontal force acting on the coin (ignoring air resistance). So, the trajectory is a straight vertical line — up and down.
> Think: Like tossing a ball while standing still — it goes up and down vertically.
#### b) Draw the trajectory of the coin from Matthew’s frame of reference.
Answer (description):
Matthew sees the bus moving forward. When Tim tosses the coin, the coin already has the same forward horizontal velocity as the bus (and Tim). As it moves upward and downward under gravity, it continues moving forward at constant horizontal speed. So, the trajectory is a parabola — like a projectile launched horizontally.
> Think: Like throwing a ball sideways off a moving car — it follows a curved path through the air.
---
5) Tara is a pilot dropping a bomb on an enemy storage depot. Annie is on the ground watching. Air resistance is small.
#### a) Draw the trajectory of the bomb from Tara’s frame of reference.
Answer (description):
Tara is flying with the plane, which is moving forward at constant speed. When she drops the bomb, it has the same horizontal velocity as the plane. From her perspective, the bomb falls straight down — because she and the bomb are moving together horizontally. So, the trajectory is a straight vertical line downward.
> Think: Like dropping a package out of a helicopter hovering over a target — it falls straight down relative to the helicopter.
#### b) Draw the trajectory of the bomb from Annie’s frame of reference.
Answer (description):
Annie is on the ground, so she sees the plane moving forward. When the bomb is dropped, it retains the plane’s forward horizontal velocity and begins falling due to gravity. So, the trajectory is a parabolic arc, starting at the drop point and curving downward as it travels forward.
> Think: Like launching a cannonball horizontally — it follows a parabola.
---
6) An old-fashioned physics dilemma: If a sailor in the crow’s nest (high up) of a sailing ship moving at constant speed drops a tool onto the deck, would it land directly beneath where he dropped it, or further back? Explain.
Answer:
The tool will land directly beneath where the sailor dropped it — assuming the ship is moving at constant speed (no acceleration) and ignoring air resistance.
Explanation:
When the sailor drops the tool, the tool already has the same horizontal velocity as the ship (because it was carried along with the ship). Once dropped, no horizontal forces act on it (air resistance ignored), so it maintains that horizontal velocity. Meanwhile, the ship continues moving forward at the same speed. Therefore, the tool and the ship move forward together — so the tool lands right below the drop point.
This illustrates the principle of inertia (Newton’s First Law): objects in motion stay in motion with the same speed and direction unless acted upon by an external force. Since the tool and the ship share the same horizontal motion, they remain aligned vertically.
> Historical note: This problem was used to argue against the idea that the Earth rotates — people thought if Earth rotated, a dropped object should land behind. But Galileo showed that objects inherit the motion of the Earth, just like the tool inherits the motion of the ship.
---
✔ Summary Key Concepts:
- Motion is relative — always measured with respect to a frame.
- Observers in their own frame consider themselves at rest.
- Objects retain horizontal velocity when dropped (if no air resistance).
- Trajectories differ depending on the observer’s motion.
Let me know if you’d like diagrams sketched or explanations for Part 2!
Parent Tip: Review the logic above to help your child master the concept of relative motion worksheet.
