The correct answer for this problem is c
1) The average velocity is 
2) The instantaneous velocity is 
Explanation:
1)
The average velocity of an object is given by

where
d is the displacement
t is the time elapsed
In this problem, the position of the particle is given by the function

where t is the time.
The position of the particle at time t = 6 sec is

While the position at time t = 12 sec is

So, the displacement is

And therefore the average velocity is

2)
The instantaneous velocity of a particle is given by the derivative of the position vector.
The position vector is

By differentiating with respect to t, we find the velocity vector:

Therefore, the instantaaneous velocity at any time t can be found by substituting the value of t in this expression.
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In order to completely describe a velocity,
you need a speed and a direction.
Answer:
An <u>applied force</u> is a force that is applied to an object by a person or another object. If a person is pushing a desk across the room, then there is an applied force acting upon the object. The applied force is the force exerted on the desk by the person.
A <u>friction force</u> is the force exerted by a surface as an object moves across it or makes an effort to move across it. There are at least two types of friction force - sliding and static friction. Though it is not always the case, the friction force often opposes the motion of an object. For example, if a book slides across the surface of a desk, then the desk exerts a friction force in the opposite direction of its motion. Friction results from the two surfaces being pressed together closely, causing intermolecular attractive forces between molecules of different surfaces. As such, friction depends upon the nature of the two surfaces and upon the degree to which they are pressed together. The maximum amount of friction force that a surface can exert upon an object can be calculated using the formula below:
= µ •
The percentage error in his experimental value is -51.97%.
<h3>What is percentage error?</h3>
This is the ratio of the error to the actual measurement, expressed in percentage.
To calculate the percentage error of the student, we use the formula below.
Formula:
- Error(%) = (calculated value-accepted value)100/(accepted............. Equation 1
From the question,
Given:
- Calculated value = 4.15 g/cm
- accepted value = 8.64 g/cm
Substitute these values into equation 1
- Error(%) = (4.15-8.64)100/8.64
- Error(%) = -4.49(100)/8.64
- Error(%) = -449/8.64
- Error(%) = -51.97 %
Hence, The percentage error in his experimental value is -51.97%.
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