I think it is a, b, and e. Hope it helps! :)
Answer:
The magnitude of the force of friction equals the magnitude of my push
Explanation:
Since the crate moves at a constant speed, there is no net acceleration and thus, my push is balanced by the frictional force on the crate. So, the magnitude of the force of friction equals the magnitude of my push.
Let F = push and f = frictional force and f' = net force
F - f = f' since the crate moves at constant speed, acceleration is zero and thus f' = ma = m (0) = 0
So, F - f = 0
Thus, F = f
So, the magnitude of the force of friction equals the magnitude of my push.
Because it helps the nail to enter an object
Time/sec. the x-axis is always the independent variable.
Answer:
C) Pnew=Poriginal/9
Explanation:
From the given conditions:
Original area, 
New area of the barrel bottom panel after increasing by a factor of 3:

On increasing the radius the area now becomes:


As we know that there will be no increase in the down-force since the height remains constant.
Pressure is given as:

∴New pressure:

