Instantaneous velocity problem

[BeckyStar678]

Homework Statement

find the instantaneous velocity of the particle described in figure 1.1 at the following time a.) t=3.0 s.

Homework Equations

instantaneous velocity equals dx/dt
in the graph, 3 seconds of time is equal to 8 meters.

The Attempt at a Solution

so would the answer just be the derivitive of 8/3? i don't get how to use the formula. because then the answer would just be zero, right?

 

[ritwik06]

Homework Statement

find the instantaneous velocity of the particle described in figure 1.1 at the following time a.) t=3.0 s.

Homework Equations

instantaneous velocity equals dx/dt
in the graph, 3 seconds of time is equal to 8 meters.

The Attempt at a Solution

so would the answer just be the derivitive of 8/3? i don't get how to use the formula. because then the answer would just be zero, right?

dx/dt gives you the slope of the tangent drawn to point at which you need the instantaneous speed. I presume that you have a displacement versus time graph. Draw a tangent to the point at t=3 and fine the slope of the tangent.
Otherwise more accurately, if you could express displacement as a function of time from the structure of the graph an then differentiate it, it would be better.
regards,
Ritwik

 

[rado5]

if the acceleration is zero (a=0) then x=v*t+x₀ so the answer is 8=v*3+x₀ and if x₀=0 then the answer is v=8/3
and also v=dx/dt then dx=v*dt and if you integrate this equation you will get x-x₀=v*t