Answer:
<u>The number is 67</u>
Step-by-step explanation:
<u>Equations</u>
Let's consider the number 83. The tens digit is 8 and the unit digit is 3. Note the tens digit's addition to the number is 80, and the unit's addition is 3. This means the tens digit adds 10 times its value, that is, 83 = 8*10 + 3.
Now, let's consider the number ab, where a is the tens digit, and b is the unit digit. It follows that
Number=10*a+b
The question gives us two conditions:
1) The sum of a two-digits number is 13.
2) The tens digit is 8 less than twice the units digit.
The first condition can be expressed as:
a + b = 13 [1]
And the second condition can be written as:
a = 2b-8 [2]
Replacing [2] into [1], we have:
2b-8 + b = 13
Operating:
3b = 13 + 8
3b = 21
Solving for b:
b = 21 / 3 = 7
Substituting into [2]:
a = 2*(7) - 8 = 6
Thus, the number is 67
I am old, so I like to use paper & pencil
Answer:
Rolling case achieves greater height than sliding case
Step-by-step explanation:
For sliding ball:
- When balls slides up the ramp the kinetic energy is converted to gravitational potential energy.
- We have frictionless ramp, hence no loss due to friction.So the entire kinetic energy is converted into potential energy.
- The ball slides it only has translational kinetic energy as follows:
ΔK.E = ΔP.E
0.5*m*v^2 = m*g*h
h = 0.5v^2 / g
For rolling ball:
- Its the same as the previous case but only difference is that there are two forms of kinetic energy translational and rotational. Thus the energy balance is:
ΔK.E = ΔP.E
0.5*m*v^2 + 0.5*I*w^2 = m*g*h
- Where I: moment of inertia of spherical ball = 2/5 *m*r^2
w: Angular speed = v / r
0.5*m*v^2 + 0.2*m*v^2 = m*g*h
0.7v^2 = g*h
h = 0.7v^2 / g
- From both results we see that 0.7v^2/g for rolling case is greater than 0.5v^2/g sliding case.
Answer:
width=2 ft, length=(3x+4)ft
Area of Rectangle=width x length
=2ft . (3x+4)ft
=6x+8 ft sq
Area of Rectangle <56 ft sq
6x+8 ft sq <56 ft sq
6x < 56 ft sq - 8 ft sq
6x < 48 ft sq Substeracting 8 on both sides
6x/6 < 48 ft sq/6 Dividing by 6 on both sides
x < 8 ft sq
Step-by-step explanation:
-2x^2-8 is the answer good luck
