Newton's Laws of Motion on a rocket

In summary, The captain adjusts the engine thrust so that the rocket slows down at the rate of 2.50m/s^2, causing a downward acceleration force on the 8.00-kg instrument hanging by a vertical wire inside the spaceship. The free-body diagram for the instrument shows that the weight of the instrument, w=mg, acts downwards while the tension, T, acts upwards. The force equation, mg - T = 2.5*8, is incorrect as the tension should be calculated as T = m*(g+2.5) due to the added acceleration force.
  • #1
plshelpme
3
0
Suppose the rocket is coming in for a vertical landing at the surface of the earth. The captain adjusts the engine thrust so that rocket slows down at the rate of 2.50m/s^2 . A 8.00-kg instrument is hanging by a vertical wire inside a space ship.

1]Draw a free-body diagram for the instrument.

2]Find the force that the wire exerts on the instrument.
 
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  • #2
Welcome to PF.

I wonder why you didn't use the template that is provided when you make a new post... anyway, what did you come up with?
What does your free body diagram look like? Which forces are acting on the block, in what directions and possibly magnitudes?
 
  • #3
CompuChip said:
Welcome to PF.

I wonder why you didn't use the template that is provided when you make a new post... anyway, what did you come up with?
What does your free body diagram look like? Which forces are acting on the block, in what directions and possibly magnitudes?

w=mg acting on the instrument downwards. tension acting upwards. with a downward accelerating force.

my attempted ans for qn 2 is mg - T = 2.5 * 8. gives the wrong tension result...

can enlight me on where the mistake lies?
 
  • #4
If the rocket is slowing, then the acceleration of the rocket is 2.5 upwards. This means that the Tension will be mg+2.5m = T = m*(g + 2.5)

Even though the ship has downward velocity - in the direction of gravity - I read it that the speed is slowing at 2.5, hence this will create a force (m*a) in addition to gravity that will add to the force of gravity in the tension on the instrument won't it?
 

FAQ: Newton's Laws of Motion on a rocket

What are Newton's Laws of Motion?

Newton's Laws of Motion are three physical laws that describe the relationship between an object's motion and the forces acting upon it. These laws were developed by Sir Isaac Newton and are fundamental principles in the study of physics.

How do Newton's Laws apply to a rocket?

Newton's Laws apply to a rocket in the same way they apply to any other object. The first law states that an object will remain at rest or in motion at a constant velocity unless acted upon by an external force. In a rocket, this means that the rocket will stay still or continue traveling at a constant speed unless a force, such as the thrust from the engines, is applied.

What is the first law of motion on a rocket?

The first law of motion on a rocket is that the rocket will remain at rest or in motion at a constant velocity unless acted upon by an external force. This means that a rocket will stay on the launchpad until the engines are ignited, and it will continue traveling at a constant speed unless additional forces, such as gravity or air resistance, act upon it.

How does Newton's Second Law apply to a rocket?

Newton's Second Law states that the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to its mass. In the case of a rocket, this means that the more force (thrust) applied to the rocket, the greater its acceleration will be. However, as the rocket's mass decreases due to fuel consumption, its acceleration will increase.

What is the Third Law of Motion on a rocket?

The Third Law of Motion states that for every action, there is an equal and opposite reaction. This means that as the rocket's engines exert a force to propel it forward, there is an equal and opposite force pushing back on the engines, causing the rocket to move in the opposite direction. This is why rockets have a large exhaust of gases shooting out of the bottom during liftoff.

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