Data:
h=25 m
v₀=0 m/s
g=9,8 m/s²
we use this formula
h=h₀+v₀.t+(1/2).g.t²
25 m=0 m+0 m/s.t+(1/2).(9,8 m/s²).t²
25 m=4,9 m/s².t²
t²=25 m /4,9 m/s²
t²=5,1 s²
t=√(5,1 s²)=2,26 s
Now, we calculate the última velocity
v=v₀+gt
v=0 m/s+9,8 m/s².(2,26 s)=22,14 m/s≈22 m/s
solution: c.) 22 m/s
Pretty sure it is B.
Because inertia is a tendency to do nothing or remain unchanged.
<u>#2</u>
Use the formula ... Kinetic energy = (1/2) x (mass) x (speed)²
<u>#3 - a).</u>
sun => energy travels as electromagnetic waves => reaches Earth as
heat & light energy.
sun => absorbed in plants => eaten by animals => animals die =>
decay into oil in millions of years => we burn the oil to get the energy.
<u>#3 - b).</u>
food I ate for lunch => metabolized into glucose by my body
=> some of it burned in my muscles to generate energy for immediate needs
=> the rest of it stored as fat for future needs.
<u>#3 - c).</u>
flower pot rolls off the ledge => gravity does work on it all the way down,
producing the kinetic energy it has when it hits the floor.
<u>#3 - d).</u>
oil or natural gas is burned, releasing heat energy => energy is used
to generate electricity => electricity flows through cables from the
power generating plant to your home => hot plate plugged into the
wall => turns electrical energy back into heat energy => heat energy
is conducted into the bottom of the beaker, flows through the glass
to the inside surface => heat energy is conducted from the inside of
the glass to the water, which gets hotter as it absorbs more energy.
=============================
<u>Note:</u>
#1 on the sheet is wrong.
"Work = force x distance" that's correct
But 25-kg is the <em>mass</em> of the ball, <em>not </em>the gravitational <em>force </em>on it.
The force on it is (mass) x (gravity), called its "weight".
That's (25-kg) x (9.8 m/s²) = 245 kg-m/s² = 245 newtons .
Electric motors require electricity to move the motor parts and do work (like an electric fan).
Elecgric generators actually burn diesel fuel to spin a motor around and around and around to GENERATE, or MAKE, electricity that you can then use to power your fans and lights in your house.
Answer:
The Chinese government wish to keep the currency undervalued because: A weaker exchange rate makes exports more competitive and increases demand for Chinese exports. Chinese economic growth is dependent on exports, so the value of the currency plays a key role in boosting growth.
Explanation:
