Let's assume that ground level is the height 0 meters. The change in potential energy is going to be gravitational potential energy, which is given by PE=mgh.
ΔPE=mgh-mgy
=mg(h-y)
=50(28-0)
=1400 J
Answer:
b. 600,000 J
Explanation:
Applying the law of conservation of energy,
The thermal energy created = Kinetic energy of the suv.
Q' = 1/2(mv²)............... Equation 1
Where Q' = Thermal energy, m = mass of the suv, v = velocity of the suv.
From the question,
Given: m = 3000 kg, v = 20 m/s
Substitute these values into equation 1
Q' = 1/2(3000×20²)
Q' = 600000 J
Hence the right option is b. 600,000 J
The addition of heat energy to a
system always causes the temperature of that system to increase. This is always
true because you are adding heat of a substance to increase its temperature. For example, you are going
to drink a cup of coffee. And you wanted it hot to boost your attention. So you
have to use hot water. In order for your water to become hot or warm, you need
boil it in a kettle. Note that you are going to use an electric stove. The
electric stove gets it energy from the source giving it a hotter temperature to
the water in the kettle. You are applying heat energy to warm the water. So,
the statement is true.
When the spring is extended by 44.5 cm - 34.0 cm = 10.5 cm = 0.105 m, it exerts a restoring force with magnitude R such that the net force on the mass is
∑ F = R - mg = 0
where mg = weight of the mass = (7.00 kg) g = 68.6 N.
It follows that R = 68.6 N, and by Hooke's law, the spring constant is k such that
k (0.105 m) = 68.6 N ⇒ k = (68.6 N) / (0.105 m) ≈ 653 N/m
A coil of wire with a current flowing thru it becomes a magnet
