Three short square wood blocks measuring 3.5 per side support a machine weighing 29500 lbs. What is the compressive stress in th
1 answer:
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Answer:
Explanation:
Using the conservation of energy we have:
Let's solve it for v:
So the speed at the lowest point is
Now, using the conservation of momentum we have:
Therefore the speed of the block after the collision is
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Answer:
-4.0 N
Explanation:
Since the force of friction is the only force acting on the box, according to Newton's second law its magnitude must be equal to the product between mass (m) and acceleration (a):
(1)
We can find the mass of the box from its weight: in fact, since the weight is W = 50.0 N, its mass will be
And we can fidn the acceleration by using the formula:
where
v = 0 is the final velocity
u = 1.75 m/s is the initial velocity
t = 2.25 s is the time the box needs to stop
Substituting, we find
(the acceleration is negative since it is opposite to the motion, so it is a deceleration)
Therefore, substituting into eq.(1) we find the force of friction:
Where the negative sign means the direction of the force is opposite to the motion of the box.