The weightlifter's internal store of energy decreased when he lifted the bar. The bar's internal store of energy increased by a smaller amount.
Explain why.

The energy returns to the weightlifter's muscles, where it is dissipated as heat.

Explanation:

The energy returns to the weightlifter's muscles, where it is dissipated as heat. As long as the weightlifter controls the weight's descent, their muscles are acting as an overdamped shock absorber, as if the weight were sitting on a piston containing very thick fluid, slowly compressing it downward (and slightly heating up the fluid in the process). Since muscles are complicated biological systems and not simple pistons, they require metabolic energy to maintain tension throughout the controlled descent, so the weightlifter feels like they're putting energy into the weight, even though the weight's gravitational potential energy is being converted into heat within the lifter's muscles.

The answer fr the following problem is mentioned below.

Explanation:

Given:

no of moles (n) = 0.63 moles

We know;

no.of molecules at STP condition ()= 6.023 ×10^23

To solve:

no of molecules(N)

We know;

to calculate no of molecules present,the formula is mentioned below as follows:

From the ideal gas equation,

n = N ÷

where,

n = no of moles

N = no of molecules

= no of molecules at STP conditions(Avogadro number)= 6.023 ×10^23 molecules

0.63 = N ÷ 6.023 ×10^23

N = 0.63 × 6.023 × 10^23

N = 3.79449 × 10^23 molecules

Therefore no of molecules present are 3.79449 × 10^23 molecules