How did people years ago find out which side of a magnet was north and which was south?

A box of books is in the floor. The following picture shows a push and a pull acting in the box.

nataly862011 [7]

Net force = 50 + 50 = 100 M
Since two forces act towards the same direction , total force should be their sum amd towards the same direction as the two forces

8 0

3 years ago

What is the half-life of a radioactive isotope that decreases to one fourth its original amount in 18 months

just olya [345]

9 months, because half of 18 is 9

7 0

3 years ago

A coffee-cup calorimeter is used to determine the heat of reaction for the reaction of compound A with compound B. A(aq) + B(aq)

Sergeeva-Olga [200]

Answer:

$\rm 1.64\times 10^{3}\; J$ .

Explanation:

Assume that his calorimeter is sufficiently effective, such that no heat had escaped to the surroundings. Heat from this solution would be absorbed by either

the solution, or
the coffee cup.

Temperature change: $33.637 - 23.722 = \rm 9.915\; ^\circ C$ .

<h3>Heat absorbed by the solution:</h3>

Only the specific heat capacity (per unit mass) of the solution is given. Both the mass of the solution and the temperature change will be required for determining the energy change. Start by finding the mass of the solution.

$m = \rho \cdot V = 2\times 16.10 \times 1.00 = \rm 32.10\; g$ .

Calculate the amount of heat absorbed from the specific heat:

$Q = c\cdot m \cdot \Delta T = 4.814\times 32.10 \times 9.915 = \rm 1335.80\; J$ .

<h3>Heat absorbed by the coffee cup:</h3>

The heat capacity of the coffee cup is given. Only the temperature change will be required for finding the amount of heat absorbed.

$Q = C\cdot \Delta T = \rm 30.7\times 9.915 = 304.391\; J$ .

<h3>Heat that this reaction produces</h3>

Find the sum of the two parts of heat. Round to three significant figures as in the heat capacity of the coffee cup and the density of the solution.

$\rm 1335.80+ 304.391 = 1.64\times 10^{3}\; J$ .

8 0

4 years ago

Question 10 of 10<br> Closure is the process of:

pshichka [43]

Answer:

Closure is the process of: Closing

Explanation:

Please visit my church's website at fbcinterlaken.org to learn more about God. Please subscribe to the You Tube channel because my church really needs the support right now. Thank you! And have a nice day! :) (I will take brainliest).

3 0

3 years ago

In April 1974, Steve Prefontaine completed a 10 km race in a time of 27 min, 43.6 s. Suppose "Pre" was at the 8.13 km mark at a

SOVA2 [1]

Answer: $0.084 m/s^2$