Explaining Newton's First Law & the Dropped Weight Trolley

Thread starter pkc111
Start date Apr 30, 2006
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First law Law Newton's first law

In summary, the question asks whether the velocity of a trolley will decrease, increase, or stay the same when a weight is dropped onto it. The answer is that it will decrease due to the law of conservation of momentum. This may seem to contradict Newton's first law, but it can be explained by considering external forces such as friction. If the experiment were done on a frictionless surface, the trolley would not experience any change in velocity. Additionally, conservation of momentum is implied in Newton's first law, and for situations where mass is not constant, Newton's law must be applied in its differential form.

Apr 30, 2006

arildno

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As a note, in the elastic collision between an object A (approaching B with velocity V) and B (at rest initially) where external forces are negligible, the final velocities are:
For Object A: (m-M)/(M+m)V, For B: 2mV/(M+m)
where m is the mass of A and M the mass of B.

Thus, if M>>m, Object A will effectively reverse its velocity, whereas B remains practically at rest.

<h2>1. What is Newton's First Law?</h2><p>Newton's First Law, also known as the Law of Inertia, states that an object at rest will remain at rest and an object in motion will remain in motion at a constant velocity, unless acted upon by an external force.</p><h2>2. How does Newton's First Law apply to the Dropped Weight Trolley?</h2><p>In the Dropped Weight Trolley experiment, the trolley is at rest until the weight is dropped, causing the trolley to move. This is because the trolley has a tendency to remain at rest, but the force of the weight dropping overcomes this tendency and causes the trolley to move.</p><h2>3. What is the significance of the Dropped Weight Trolley experiment in understanding Newton's First Law?</h2><p>The Dropped Weight Trolley experiment demonstrates the concept of inertia, which is a key aspect of Newton's First Law. It shows that objects have a natural tendency to resist changes in their state of motion, and that an external force is required to change this state.</p><h2>4. Are there any real-life applications of Newton's First Law?</h2><p>Yes, Newton's First Law has many real-life applications. It helps explain why objects stay in motion until acted upon by a force, such as a car continuing to move forward after the engine is turned off. It also explains why we wear seatbelts in cars, as they prevent us from continuing to move forward when the car suddenly stops.</p><h2>5. Are there any limitations to Newton's First Law?</h2><p>Newton's First Law is a simplified model of motion and does have some limitations. It only applies to objects moving at a constant velocity, and does not account for objects experiencing acceleration. Additionally, it assumes that there are no external forces acting on the object, which may not always be the case in real-life situations.</p>

FAQ: Explaining Newton's First Law & the Dropped Weight Trolley

1. What is Newton's First Law?

Newton's First Law, also known as the Law of Inertia, states that an object at rest will remain at rest and an object in motion will remain in motion at a constant velocity, unless acted upon by an external force.

2. How does Newton's First Law apply to the Dropped Weight Trolley?

In the Dropped Weight Trolley experiment, the trolley is at rest until the weight is dropped, causing the trolley to move. This is because the trolley has a tendency to remain at rest, but the force of the weight dropping overcomes this tendency and causes the trolley to move.

3. What is the significance of the Dropped Weight Trolley experiment in understanding Newton's First Law?

The Dropped Weight Trolley experiment demonstrates the concept of inertia, which is a key aspect of Newton's First Law. It shows that objects have a natural tendency to resist changes in their state of motion, and that an external force is required to change this state.

4. Are there any real-life applications of Newton's First Law?

Yes, Newton's First Law has many real-life applications. It helps explain why objects stay in motion until acted upon by a force, such as a car continuing to move forward after the engine is turned off. It also explains why we wear seatbelts in cars, as they prevent us from continuing to move forward when the car suddenly stops.

5. Are there any limitations to Newton's First Law?

Newton's First Law is a simplified model of motion and does have some limitations. It only applies to objects moving at a constant velocity, and does not account for objects experiencing acceleration. Additionally, it assumes that there are no external forces acting on the object, which may not always be the case in real-life situations.