Is the Net Force Zero in Constant Velocity and Other Physics Queries?

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The discussion focuses on the evaluation of several physics statements regarding net force and motion. It confirms that a net force acting on an object at constant velocity is zero, while a net force will change an object's velocity. The need for a net force to maintain constant velocity is debated, with clarification that acceleration can be zero without requiring a force. The equal and opposite forces during collisions are affirmed, while the relationship between acceleration and force is questioned. Overall, the thread emphasizes the application of Newton's second law to clarify these concepts.
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Homework Statement


Indicate whether the following statements are always true or can be false. (Select T-True, F-False. If the first is F and the rest T, enter FTTTTT).

A) The net force which acts on an object which maintains a constant velocity is zero.
B) If a net force acts on an object, the object's velocity will change.
C) In order not to slow down, a truck moving at a constant velocity needs a small net force applied.(ignore friction)
D) If an object's speed does not change, no net force is acting on the object.
E) During the collision of a large truck with a car, the car exerts an equal size force on the truck as the truck exerts on the car.
F) If two object have the same acceleration, they are under the influence of equal forces.


Homework Equations



F=ma

The Attempt at a Solution


A) True--> if constant velocity= 0 acceleration and F=m(0)= 0
B) ?
C)False--> acceleration can be zero and still keep a constant velocity
D)True? why
E)True--> equal and opposite forces
F)True? why
 
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JLPG said:

Homework Statement


Indicate whether the following statements are always true or can be false. (Select T-True, F-False. If the first is F and the rest T, enter FTTTTT).

A) The net force which acts on an object which maintains a constant velocity is zero.
B) If a net force acts on an object, the object's velocity will change.
C) In order not to slow down, a truck moving at a constant velocity needs a small net force applied.(ignore friction)
D) If an object's speed does not change, no net force is acting on the object.
E) During the collision of a large truck with a car, the car exerts an equal size force on the truck as the truck exerts on the car.
F) If two object have the same acceleration, they are under the influence of equal forces.

Homework Equations



F=ma

The Attempt at a Solution


A) True--> if constant velocity= 0 acceleration and F=m(0)= 0
B) ?
C)False--> acceleration can be zero and still keep a constant velocity
D)True? why
E)True--> equal and opposite forces
F)True? why
What do you want from us?

Some of your answers are correct. Others are not.

Can velocity change without speed changing?
 
Of the 5 you attempted, you have three correct. Hint: Apply Newton 2.
 
Thank-you, I figured it out.
T
T
F
F
T
F
:)
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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