where does 4.90s come from when t when t was given as 4.20s? forcex=t^4-5t=4.20^4-5(4.20)=290

forcey=7t^2+1=7*(4.90)^2 +1=169

force=sqrt(forcex^2+forcey^2)=336 N

To understand where the value of 4.90s comes from, let's break down the calculation step by step.

Given:
t = 4.20s

You mentioned an equation:
forcex = t^4 - 5t

To find the value of forcex, we substitute t = 4.20s into the equation:
forcex = (4.20)^4 - 5(4.20)
forcex = 17.576 - 21
forcex = -3.424

So, we have found that forcex is equal to -3.424.

Next, you mentioned another equation:
forcey = 7t^2 + 1

Again, substituting the value of t = 4.20s into the equation:
forcey = 7(4.20)^2 + 1
forcey = 7(17.64) + 1
forcey = 123.48 + 1
forcey = 124.48

So, forcey is equal to 124.48.

Now, we can calculate the total force:

force = sqrt(forcex^2 + forcey^2)
force = sqrt((-3.424)^2 + (124.48)^2)
force = sqrt(11.723776 + 15479.4304)
force = sqrt(15491.154176)
force ≈ 393.56

Therefore, when t is given as 4.20s, the total force is approximately 393.56N. The value of 4.90s mentioned in your question is not directly related to this calculation.