What is the Velocity of a Block Pushed by a Linear Force Function?

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Homework Help Overview

The problem involves determining the velocity of a block being pushed by a time-dependent linear force function, specifically F(t) = t, with a given mass and no friction. The context is rooted in classical mechanics, particularly Newton's second law.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the implications of a non-constant acceleration due to the time-dependent force. There is an exploration of how to correctly relate force, mass, and acceleration over time, with attempts to derive velocity from acceleration.

Discussion Status

The discussion is active, with participants clarifying the relationship between force, acceleration, and velocity. Some guidance has been offered regarding the correct interpretation of the force function and its impact on acceleration and velocity calculations.

Contextual Notes

There is an assumption that the block starts from rest, which is relevant to the calculations of velocity. Participants are also questioning the integration process and the treatment of time in their equations.

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Homework Statement



A force of F(t) = t is pushing a block of 5kg mass with no friction. What is the velocity after 10 seconds?

Homework Equations



F=ma

The Attempt at a Solution




F(10) = 10 N

a = F/m = 10/5 = 2 m/s^2

a = dv/dt

v(t) = 2t

v(10) = 20 m/s


I've calculated the acceleration by plugging in the time into F(t) and integrated the acceleration to find v(t). But when I plug in the time again into v(t), is that the right step?
 
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The acceleration is not constant, 2m/s2. If the force depends on t so does the acceleration, as it is a=F/m.

ehild
 
So I should carry the t in the force and set a(t) = F(t) / m ?
a(t) = t / 5

v(t) = t^2 / 10
v(10) = 10 m/s?
 
Supposing that the block had 0 velocity at the beginning, your result is correct.

ehild
 
ahh thank you
 

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