A 1 kg ball and a 10 kg ball are dropped from a height of 10 m at the same time. In the absence of air resistance,
1 answer:
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Answer:
19.8 J
Explanation:
According to the law of conservation of energy, the total mechanical energy of the spring (sum of kinetic energy and elastic potential energy) must be conserved:
(1)
where we have
is the initial kinetic energy of the spring, which is zero because the spring starts from rest (2)
is the elastic potential energy of the spring when it is fully stretched
is the kinetic energy of the spring when it reaches the natural length
is the elastic potential energy of the spring when it reaches its natural length, which is zero because the stretch in this case is zero (3)
So
where
k = 440 N/m is the spring constant
is the initial stretching of the spring
Substituting,
And so using eq.(1) and keeping in mind (2) and (3) we find
Answer:
The cart will accelerate to the left
Explanation:
The cart is initially at rest. In order to understand its motion, we should consider the net force acting on the cart. We have two forces acting on it:
- A force of 7 N to the left
- A force of 5 N to the right
Therefore, the net force is
in the direction of the stronger force (so, to the left).
According to Newton's second law:
a net force different from zero produces an acceleration of the object, in the same direction as the net force. Therefore, the cart will accelerate to the left.