Here when an object is placed on the level floor then in that case there are two forces on the object
1). Weight of object downwards (mg)
2). Normal force due to floor which will counterbalance the weight (N)
so when no force is applied on the box at that time normal force is counter balanced by weight.
Now here it is given that A person tried to lift the box upwards
So now there are two forces on the box
1). Applied force of person
2). Normal force due to ground
So now these two forces will counter balance the weight of the crate
So we can write an equation for force balance like

given that

here
m = 30 kg and
g = acceleration due to gravity = 10 m/s^2

now from above equation


So force applied by the person must be 150 N
Water is more dense then air so it sorta holds the rock as it sinks
The liquid is called condensation and its generally formed when water vaor in the air cools down rapidly and collects around or on an object forming water droplets.
No i took the test and the answer is actually homogenous mixture
Answer:
500000N/m²
5250N
Explanation:
Given parameters:
Depth(H) = 50m
Density of water = 1000kg/m³
Acceleration of free fall = 10m/s
Unknown:
Pressure the water exerts on the diver = ?
Solution:
Pressure is the force per unit area on a body. In fluids, pressure is the product of density, gravity and height
Pressure in fluids = Density x acceleration due to gravity x height
Input the variables and solve;
Pressure in fluids = 1000 x 10 x 50 = 500000N/m²
B.
width of window = 150mm
height of window = 70mm
Force water exerts on the window = ?
To solve this problem;
Pressure = 
Area of the window = width x height = 150 x 10⁻³ x 70 x 10⁻³
= 1.05 x 10 ⁻²m²
Force = pressure x area
Input the variables;
= 500000N/m² x 1.05 x 10 ⁻²m²
= 5250N