Number 4 I think
the atomic mass is 11 because the mass is the sum of protons and neutrons
Answer:0.27
Explanation:
Given
One worker Pushes with force 
other Pulls it with a rope of rope 
mass of crate 
both forces are horizontal and crate slides with a constant speed
Both forces are in the same direction so Friction will oppose the forces and will be equal in magnitude of sum of two forces because crate is moving with constant speed i.e. net force is zero on it

where
is the friction force



where
is the coefficient of static friction



Answer:
2.73414 seconds
467622.66798 J
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity
s = Displacement
g = Acceleration due to gravity = 9.81 m/s² = a



or

The time taken is 2.73414 seconds
The potential energy is given by

The change in potential energy is 467622.66798 J
A.) <span>If no unbalanced force acts upon the house of cards, then it will remain standing forever.
[ Other Statements doesn't make any sense in Physics, they can be true in some situation & can't be false, option A is the only answer ]
Hope this helps!</span>