Answer:
1/8 = (1/2)^3
This implies the sample has decayed for 3 half lives
3 * 5730 yrs = 17,200 years
The complete sentence is:
A calorimeter directly measures changes in temperature in order to calculate specific heat.
In fact, the amount of energy acquired/released by a substance is directly proportional to its change in temperature due to the equation

where Q is the amount of energy, m is the mass of the substance, Cs is the specific heat of the substance and
is the change in temperature. Therefore, by knowing Q, m and by measuring the change in temperature, it is possible to calculate Cs, the specific heat capacity of the substance.
Answer:the rate of change in velocity
Explanation: acceleration =the change in velocity / time taken the unit is m/s2
While velocity is the distance traveled in a given direction/time taken.the unit is m/s
Answer: The Electrostatic force of attraction or repulsion between two charges shows that the Newton's third law applies to electrostatic forces.
Explanation: Consider two Oppositely charged charges separated by distance d.
The electrostatic force exerted by charge 1 on charge 2 is.
By Coulomb's Law :
F1 = k
.....................................(1)
The electrostatic force exerted by charge 2 on charge 1 is.
F2 = - k
................................. (2)
negative sign shows that force are in opposite direction.
From Equation 1 and 2
F1 = - F2
Which implies Newton Third law.
The non-relativistic formula for low speed v < 0.1c is:
K.E = 0.5mv^2 = 0.5 * 235 * (7)^2 = 5757.5 J