___________________ is the type of exercise you are doing. Are you running, swimming, or walking?

8.)The potential energy of a 40-kg cannonball is 14000 J. How high was the cannon ball to have this much potential energy?

Delvig [45]

Hey! I empathize with you, as I just started the energy unit in physics as well!

Alright, lets list what we know, and which equation(s) we need.

PE = Gravitational Potential Energy

$PEg = mgh$

m = mass

g = gravity (9.8 m/s^2)

h = height

Guess what?

We need to find the height!

Lets make this more organized:

Known:

m = 40 kg

PE = 14000

g = 9.8 m/s^2

Unknown:

h = ?

================================

Now, if we take a look at the equation PEg = mgh, you will see that we have everything besides the height! So lets solve for the height by substituting in for the variables we know:

14000 J = 40 kg * (9.8 m/s^2) * h

40 * 9.8 = 392

14000 J = 392 * h

14000/392 = h

35.71 m = h

There we go! If you simply list what you know and don't know, you will find the equation you need to solve the problem.

Have a great day and good luck!

7 0

3 years ago

Calculate the final temperature of a mixture of 0.350 kg of ice initially at 218°C and 237 g of water initially at 100.0°C.

kramer

Answer:

115 ⁰C

Explanation:

Step 1: The heat needed to melt the solid at its melting point will come from the warmer water sample. This implies

$q_{1} +q_{2} =-q_{3}$ -----eqution 1

where,

$q_{1}$ is the heat absorbed by the solid at 0⁰C

$q_{2}$ is the heat absorbed by the liquid at 0⁰C

$q_{3}$ the heat lost by the warmer water sample

Important equations to be used in solving this problem

$q=m *c*\delta {T}$ , where -----equation 2

q is heat absorbed/lost

m is mass of the sample

c is specific heat of water, = 4.18 J/0⁰C

$\delta {T}$ is change in temperature

Again,

$q=n*\delta {_f_u_s}$ -------equation 3

where,

q is heat absorbed

n is the number of moles of water

tex]\delta {_f_u_s}[/tex] is the molar heat of fusion of water, = 6.01 kJ/mol

Step 2: calculate how many moles of water you have in the 100.0-g sample

$=237g *\frac{1 mole H_{2} O}{18g} = 13.167 moles of H_{2}O$

Step 3: calculate how much heat is needed to allow the sample to go from solid at 218⁰C to liquid at 0⁰C

$q_{1} = 13.167 moles *6.01\frac{KJ}{mole} = 79.13KJ$

This means that equation (1) becomes

79.13 KJ + $q_{2} = -q_{3}$

Step 4: calculate the final temperature of the water

$79.13KJ+M_{sample} *C*\delta {T_{sample}} =-M_{water} *C*\delta {T_{water}$

Substitute in the values; we will have,

$79.13KJ + 237*4.18\frac{J}{g^{o}C}*(T_{f}-218}) = -350*4.18\frac{J}{g^{o}C}*(T_{f}-100})$

79.13 kJ + 990.66J* $(T_{f}-218})$ = -1463J* $(T_{f}-100})$

Convert the joules to kilo-joules to get

79.13 kJ + 0.99066KJ* $(T_{f}-218})$ = -1.463KJ* $(T_{f}-100})$

$79.13 + 0.99066T_{f} -215.96388= -1.463T_{f}+146.3$

collect like terms,

2.45366 $T_{f}$ = 283.133

∴ $T_{f} =$ = 115.4 ⁰C

Approximately the final temperature of the mixture is 115 ⁰C

6 0

3 years ago

Please help on this one? I'm guessing it's either electric or mechanical? Please help.

Dmitriy789 [7]

A . Thermal

Thermal Energy, or heat, is the internal energy in substance the vibration & movement of the atoms & molecules within substances. Geothermal energy is an example of thermal energy.

3 0

3 years ago

Find the intensity of the electromagnetic wave described in each case. (a) an electromagnetic wave with a wavelength of 630 nm a

qaws [65]

Find the intensity of the electromagnetic wave described in each case.

(a) an electromagnetic wave with a wavelength of 645 nm and a peak electric field magnitude of 8.5 V/m.

(b) an electromagnetic wave with an angular frequency of 6.3 ✕ 1018 rad/s and a peak magnetic field magnitude of 10−10 T.

3 0

4 years ago

A train travels 76 kilometers in 2 hours and then 54 kilometers in 5 hours .What is the average speed ?

gizmo_the_mogwai [7]

V = d ÷ t --> bc d=vt
V = (76+54)÷(2+5) = 130÷7 = 18.57km/hr

7 0

3 years ago