Use these numbers: the cart mass is 40.0 kg, and the initial velocity (at t = 0 s ) is 3.00 m/s in the negative x direction. find the velocity of the cart at t = 30 s. (use a minus sign if the cart is moving in the negative x direction at that time.) m/s

Figure is missing: find it in attachment.

+4.50 m/s

Explanation:

The mass of the cart is

m = 40.0 kg

and its initial  velocity is

u = -3.00 m/s (negative x-direction)

The graph represents the force applied to the cart versus time. We know that the area under the graph corresponds to the impulse, which is the change in momentum of the cart. We also notice that the force applied in the two parts is constant, so we can write the impulse simply as product between the force applied and the time interval:

In the first part of the motion (from 0 s to 20 s), the force applied is F = +20 N, so the impulse (and the change in momentum) is

In the second part of the motion (from 20 s to 30 s), the force applied is

F = -10 N

So the impulse is

So the total change in momentum of the cart is

The change in momentum can be written as

where v is the final velocity of the cart. Solving for v,

So, 4.50 m/s in the positive direction.

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =

the awnser is d you right bro