Answer:
Final Speed of Dwayne 'The Rock' Johnson = 15.812 m/s
Explanation:
Let's start out with finding the force acting downwards because of the mass of 'The Rock':
Dwayne 'The Rock' Johnson: 118kg x 9.81m/s = 1157.58 N
Now the problem also states that the kinetic friction of the desk in this problem is 370 N
Since the pulley is smooth, the weight of Dwayne Johnson being transferred fully, and pulls the desk with a force of 1157.58 N. The frictional force of the desk is resisting this motion by a force of 370 N. Subtracting both forces we get the resultant force on the desk to be: 1157.58 - 370 = 787.58 N
Now lets use F = ma to calculate for the acceleration of the desk:
787.58 = 63 x acceleration
acceleration = 12.501 m/s
Finally, we can use the motion equation:
here u = 0 m/s (since initial speed of the desk is 0)
a = 12.501 m/s
and s = 10 m
Solving this we get:
Since the desk and Mr. Dwayne Johnson are connected by a taught rope, they are travelling at the same speed. Thus, Dwayne also travels at 15.812 m/s when the desk reaches the window.
Answer: 2.5 m/s and 6.25 m
Explanation:
u = 0
a = 0.5 m/s²
t = 5 s
v = u + at
= 0 + 0.5 × 5
= <u>2.5 m/s</u>
s = ut + 1/2 at²
= 1/2 × 2.5 × 5
=<u> 6.25 m</u>
It's easy raising the barbell.
Answer:
The right option is (d) substance undergoing a change of state
Explanation:
Latent Heat: Latent heat is the heat required to change the state of a substance without change in temperature. Latent heat is also known as hidden heat because the heat is not visible. The unit is Joules (J).
Latent heat is divided into two:
⇒ Latent Heat of fusion
⇒ Latent Heat of vaporization.
Latent Heat of fusion: This is the heat energy required to convert a substance from its solid form to its liquid form without change in temperature. E.g (Ice) When ice is heated, its temperature rise steadily until a certain temperature is reached when the solid begins to melts.
Latent Heat of vaporization: This is the heat required to change a liquid substance to vapor without a change in temperature. The latent heat depend on the mass of the liquid and the nature of the liquid. E.g When water is heated from a known temperature its boiling point (100°C) When more heat is supplied to its boiling temperature, it continue to boil without a change in temperature.
From The above, Latent heat brings about a change of state of a substance at a steady temperature.
The right option is (d) substance undergoing a change of state
Decomposition reactions are said to be those reactions in which a reactants breakdown into two or more products. The general reaction for decomposition reactions is as follow,
ABC → A + B + C
Specific Examples are as,
Water → Hydrogen + Oxygen
2 H₂O → 2 H₂ + O₂
Calcium carbonate → Calcium oxide + Carbon dioxide
CaCO₃ → CaO + CO₂
While, Synthetic reactions are said to be those reactions in which two or more reactants combine to form two or more products. The general reaction for synthetic reactions is as follow,
A + B + C → ABC
Specific Examples are as,
Iron + Oxygen → Iron Oxide
2 Fe + 3 O₂ → 2 Fe₂O₃
Sodium + Chlorine → Sodium chloride
2 Na + Cl₂ → 2 NaCl
Sulfur + Oxygen → Sulfur dioxide
S + O₂ → SO₂
Potassium + Chlorine → Potassium chloride
2 K + Cl₂ → 2 KCl
