Answer:
Normal Force is usually perpendicular to the movement and static friction usually means that there is no movement.
Explanation:
The work donde by any force on an object is equal to the displacement of the object multiplied by the component of the force that is in the direction of the displacement.
Normal force is usually perpendicular to the movement, so there is no component in the direction of the displacement. This is why it is zero in most circumstances.
<em>Static</em> friction on the other hand, usually means that there is no movement at all (it's static). It means that there is no displacement between the object and ground (in most cases). If there is no displacement, there is no work.
Answer:
1.5 m/s²
Explanation:
For the block to move, it must first overcome the static friction.
Fs = N μs
Fs = (45 N) (0.42)
Fs = 18.9 N
This is less than the 36 N applied, so the block will move. Since the block is moving, kinetic friction takes over. To find the block's acceleration, use Newton's second law:
∑F = ma
F − N μk = ma
36 N − (45 N) (0.65) = (45 N / 9.8 m/s²) a
6.75 N = 4.59 kg a
a = 1.47 m/s²
Rounded to two significant figures, the block's acceleration is 1.5 m/s².
Usually the coefficient of static friction is greater than the coefficient of kinetic friction. You might want to double check the problem statement, just to be sure.
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Answer:
2.48 m/s
Explanation:
We can use the kinematic equation,
s = ut +½at²
Where
s = displacement
u = initial velocity
t = time taken
a = acceleration
Using the equation in vertical direction,
321 = 0×t +½×g×t², u = 0 because initial vertical velocity is 0
We get t = 8.01 s
Using the equation in the horizontal direction,
52 = u×8.01 +½×0×(8.01)²,. a = 0 because no unbalanced force act on object in that direction
So u = 2.48 m/s
Calculate the pressure due to sea water as density*depth.
That is,
pressure = (1025 kg/m^3)*((9400 m)*(9.8 m/s^2) = 94423000 Pa = 94423 kPa
Atmospheric pressure is 101.3 kPa
Total pressure is 94423 + 101.3 = 94524 kPa (approx)
The area of the window is π(0.44 m)^2 = 0.6082 m^2
The force on the window is
(94524 kPa)*(0.6082 m^2) = 57489.7 kN = 57.5 MN approx
