Answer:
F = 0 [N]
Explanation:
To solve this problem we must perform a summation of forces in the direction of the vertical axis. Where the positive force is that of the tension of the upward force, while the force exerted by the weight is directed downward with a negative sign.
ΣF = 0
15 - 15 + F = 0
F = 0 [N]
It is the number in front of the equation
The final temperature of the block is 
Explanation:
The amount of thermal energy Q supplied to a substance is related to the increase in temperature of the substance,
, according to the equation

where:
m is the mass of the substance
is the specific heat capacity of the substance
In this problem, we have:
m = 1.2 kg is the mass of the block
is the amount of energy supplied to the block
is the specific heat capacity of the block
Solving for
, we find the increase in temperature:

And since the initial temperature was

The final temperature will be

Learn more about specific heat capacity:
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The initial velocity of the sled will be 7.34 m/sec. V is the initial velocity of the sled.
<h3>What is the law of conservation of momentum?</h3>
According to the law of conservation of momentum, the momentum of the body before the collision is always equal to the momentum of the body after the collision.
The given data in the problem is;
(m₁) mass of child = 38 kg
(u₁) is the initial velocity child = 2.2 m/s
(m₂) is the mass of sled = 68 kg
(u₂) is the initial velocity of sled = ?
(v) is the velocity after collision = 5.5 m/s
According to the law of conservation of momentum;
Momentum before collision =Momentum after collision

Hence,the initial velocity of the sled will be 7.34 m/sec.
To learn more about the law of conservation of momentum refer;
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Answer:
2.6 m/s
Explanation:
mass of Jerome (Mj) = 102 kg
mass of Micheal (Mm) = 98 kg
mass of each cart (Mc) = 14 kg
recoil speed of Jerone and Micheal after push (Vi) = ?
mass of Suzie (Ms) = 44 kg
Suzie's speed after push (Vs) = 9.6 m/s
From the conservation of momentum, initial momentum = final momentum
Since they all are initially at rest the initial momentum is 0 and hence the final momentum is also 0.
Therefore for the final momentum we have
(Mj + Mm + Mc) Vi - (Ms + Mc) Vs = 0 ( the negative sign is because they move in opposite directions)
((102 + 98 + 14) x Vi ) - ((44 + 14) x 9.6) = 0
(214 x Vi) - (58 x 9.6) = 0
214 Vi = 556.8
Vi = 556.8 / 214 = 2.6 m/s