Answer:
40m (40m east)
Explanation:
The fist move is 70m east, and east is the positive direction so the truck initially is at +70m.
The second move is 120m to the west, since east is the positive direction, west must be the negative direction, this means the truck now is at:

The third move is 90m to the east, again, this is the positive direction, so the new position is:

The truck is at + 40m, so it ended up 40m away from its initial position and this is the resultant dispacement.
After one half-life, 8 g of radioactive isotope will remain in the sample.
<h3>What is radioactivity?</h3>
The act of producing radiation spontaneously is known as radioactivity. This is accomplished by an unstable atomic nucleus that want to give up some energy in order to move to a more stable form.
The following formula is used to compute the number of half lives elapsed:

Hence,8 gram of radioactive isotope remains in the sample after 1 half-life.
To learn more about the radioactivity, refer to the link;
brainly.com/question/1770619
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We define acceleration as the rate of change of the velocity
Thus, if you have positive velocity and positive acceleration, your <u>speed increases.</u>
If you have positive velocity and negative acceleration, your speed decreases.
Now you get the idea, we will see that the correct option is graph 1.
We know that the car moves towards the right (let's define this as "the car has positive velocity") and we also know that te car is slowing down constantly (thus the acceleration needs to be negative and constant).
By looking at the graphs, the only one with these properties is graph 1.
If you want to learn more, you can read:
brainly.com/question/12550364
Answer:
1. Can change the state of an object(rest to motion/ motion to rest)
2. May change the speed of an object if it is already moving.
3. May change the direction of motion of an object.
Explanation: A force acting on an object causes the object to change its shape or size, to start moving, to stop moving, to accelerate or decelerate.