(a) -267 N
Explanation: if the refrigerator is not moving, it means that the net force acting on it is zero.
We are only interested in the motion along the horizontal direction; there are two forces acting in this direction:
- The pushing force, forward, F=+267 N
- The static frictional force, backward, 
Since the net force must be zero, we have
(b) 363.1 N
The largest pushing force that can be applied to the refrigeratore before it begins to move is equal to the magnitude of the maximum static frictional force, which is given by:
where
is the coefficient of static friction
m = 57 kg is the mass of the refrigerator
g = 9.8 m/s^2 is the gravitational acceleration
Substituting,
acceleration times time falling
25*2
50 m*s^-1
To solve this problem it is necessary to apply the concepts related to Sound Intensity. The unit most used in the logarithmic scale is the decibel and mathematically this is expressed as
Where,
= Sound intensity level in decibels
I = Acoustic intensity on the linear scale
Hearing threshold
According to the values, the total intensity is 32 times the linear intensity and the value in decibels is 83dB
So:
Therefore the sound intensity due to one person is 67.948dB
Answer:
None of the above forces on air drag on him is equal to his weight
Explanation:
In the velocity-time graph,the gradient of the curve where it is flatten shows the parachutist reaches the terminal velocity when it reaches terminal velocity which means the parachutist reaches constant velocity or speed,indicating that the acceleration of free fall(g) is zero.And according to the resultant force formula weight - air drag= mass*acceleration. so when accelerate is zero,resultant force is zero. And hence the equation will be like this: weight= air drag
