Answer:
B -- Cobalt and iron
Explanation:
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Answer:
The amount of work done required to stretch spring by additional 4 cm is 64 J.
Explanation:
The energy used for stretching spring is given by the relation :
.......(1)
Here k is spring constant and x is the displacement of spring from its equilibrium position.
For stretch spring by 2.0 cm or 0.02 m, we need 8.0 J of energy. Hence, substitute the suitable values in equation (1).

k = 4 x 10⁴ N/m
Energy needed to stretch a spring by 6.0 cm can be determine by the equation (1).
Substitute 0.06 m for x and 4 x 10⁴ N/m for k in equation (1).

E = 72 J
But we already have 8.0 J. So, the extra energy needed to stretch spring by additional 4 cm is :
E = ( 72 - 8 ) J = 64 J
The substance is DNA and it would be found in the nucleus.
Answer:
0.002372187708 kg
Explanation:
Each atom of Uranium 235 releases 200 MeV = 200×10⁶×1.60218×10⁻¹⁹
= 200×1.60218×10⁻¹³ Joule
Number of atoms in a 2.6 kg sample mass = (2.6/0.235)×6.02214076×10²³
⇒Number of atoms in a 2.6 kg sample mass = 66.627×10²³ atoms
Change in energy = Change in mass / (speed of light)²
ΔE = Δmc²
⇒200×1.60218×10⁻¹³×66.627×10²³ = Δm×(3×10⁸)²
⇒Δm = 200×1.60218×10⁻¹³×66.627×10²³/(3×10⁸)²
⇒Δm = 2372.187708×10⁻⁶ kg
∴Change in mass = 0.002372187708 kg
Im not sure, but here are a few of mine : Learn to be silent, and listen, take massive action and be proactive, listen, focus, and lastly, persist. Hope this helped! (: