The correct answer is
<span>c. one person exerts more force than the other so that the forces are unbalanced.
In fact, the door is initially at rest. In order to move the door, a net force different from zero should be applied, according to Newton's second law:
</span>

<span>where the term on the left is the resultant of the forces acting on the door, m is the door mass and a its acceleration.
In order to move the door, the acceleration must be different from zero. But this means that the resultant of the forces acting on it must be different from zero: this is possible only if the forces applied by the two persons are unbalanced, i.e. one person exerts more force than the other.</span>
Answer:
2*10^-<em>5</em>
Explanation:
<em>B=</em><em>I</em><em>L</em>
<em>I=</em><em>B</em><em>/</em><em>L</em>
<em>I=</em><em>0</em><em>.</em><em>0</em><em>0</em><em>2</em><em>0</em><em>*</em><em>1</em><em>0</em><em>^</em><em>-</em><em>4</em><em>/</em><em>1</em><em>0</em>
<em>I=</em><em>2</em><em>*</em><em>1</em><em>0</em><em>^</em><em>5</em>
Answer:
Terminal velocity of object = 12.58 m/s
Explanation:
We know that the terminal velocity is attained when drag force and gravitational force are of the same magnitude.
Gravitational force = mg = 80 * 9.8 = 784 N
Drag force = 
Equating both, we have

So v = 12.58 m/s or v = -15.58 m/s ( not possible)
So terminal velocity of object = 12.58 m/s
Answer:
2. ( b ) zero
3. ( c ) 10 s
4. Uniform then decreasing
Explanation:
2.
Since the motion is uniform, initial and final velocity will be 0, hence acceleration will be zero.
3.
Initial velocity ( u ) = 5 m/s
Final velocity ( v ) = 35 m/s
Acceleration ( a ) 3 m/s^2
To find : Time ( t )
Formula : -
t = v - u / a
= 35 - 5 / 3
= 30 / 3
t = 10 s