True or false velocity physics question double check

In summary, the object is motionless and located at x = 5.2 m with an instantaneous acceleration of -2.3 m/s2. At this instant in time, the first derivative of a position vs. time graph is zero and the second derivative is not zero. The slope of a velocity vs. time graph is negative and the object is just about to start moving backwards.
  • #1
Melchior25
30
0
So I just want to make sure I have the correct answers before I submit my question. So could anyone please just double check my answers?

Thanks

An object moves in one dimension along the x-axis. At some instant in time, the object is located at x = 5.2 m, is motionless, and has an instantaneous acceleration of -2.3 m/s2. What must be true about this object at this instant in time? (Select all that apply.)
The first derivative of a position vs. time graph at this point is zero. False
The second derivative of a position vs. time graph at this point is zero. True
The slope of a velocity vs. time graph at this point is positive. False
The slope of a velocity vs. time graph at this point is negative. True
The object is just about to start moving backwards. True
The object is just about to start moving forwards. False

Again, I just want to make sure these are right. I'm not sure if I am completely correct.
 
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  • #2
1. True. Because motionless means not moving means velocity is zero means first derivative of position towards time (ie velocity) is zero.
 
  • #3
2. False. The second derivative of position towards time means acceleration. at this point, the acceleration is not zero because it is given to you as -2.3 m/s^2.
 
  • #4
Thanks, Leong. I was actually a bit unsure about the first two. I wrote the equations out but some how had a feeling that I wasn't doing something right.
 

1. Is velocity a vector or scalar quantity?

Velocity is a vector quantity, meaning it has both magnitude and direction.

2. What is the difference between speed and velocity?

Speed is a scalar quantity that refers to the rate at which an object is moving. Velocity, on the other hand, is a vector quantity that includes both the speed and direction of an object's motion.

3. How is velocity calculated?

Velocity can be calculated by dividing the displacement (change in position) by the change in time. In equation form, it is written as v = Δx/Δt.

4. Can an object have a negative velocity?

Yes, an object can have a negative velocity if it is moving in the opposite direction of the chosen reference point or has a direction opposite to the positive direction on a coordinate system.

5. Can velocity change even if an object is moving at a constant speed?

Yes, velocity can change even if an object is moving at a constant speed if the direction of its motion changes. This is because velocity is a vector quantity that takes into account both speed and direction.

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