The answer is A) electric current ⚡️
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Rock dug out from the deep inside earth and refined.
Explanation:
Ores are usually rocks dug out from deep within the earth and refined.
An ore is an aggregate of metalliferous minerals with gangue that can be won at profit under current economic conditions.
Ores are rocks and rocks can be ores if they contain viable economic minerals.
They are usually naturally formed and they contain different minerals.
For example cassiterite is a known ore of tin.
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Answer:
the mass of the truck is 2 kg.
Explanation:
Given;
mass of the car, m₁ = 3 kg
initial velocity of the car, u₁ = 40 m/s
initial velocity of the truck, u₂ = 60 m/s
let the mass of the truck = m₂
Apply the principle of conservation of linear momemtum;
m₁u₁ = m₂u₂
m₂ = (m₁u₁) / u₂
m₂ = (3 x 40) / (60)
m₂ = 2 kg
Therefore, the mass of the truck is 2 kg.
Answer:
a. Walking burns up more energy.
b. 1740 kJ
c. This is because more intense exercise releases a lot of energy in a short period of time, whereas, less intense energy releases it energy gradually over a long period of time.
Explanation:
a. We know energy W = Pt where P = power and t = time.
Now for walking, t = d/v where d = distance = 5.00 km and v = speed = 3.00 km/hr and P = 290 W
So, t = d/v = 5.00 km/3.00 km/hr = 5/3 hr = 5/3 × 3600 s = 6000 s
W = Pt = 290 W × 6000 s = 1740000 = 1740 kJ
Now for running, t = d/v where d = distance = 5.00 km and v = speed = 10.00 km/hr
So, t = d/v = 5.00 km/10.00 km/hr = 0.5 hr = 0.5 × 3600 s = 1800 s and P = 700 W
W = Pt = 700 W × 1800 s = 1260000 = 1260 kJ
Since walking burns up 1740 kJ and running burns up 1260 kJ, walking burns up more energy.
b. It burns up 1740 kJ
c. This is because more intense exercise releases a lot of energy in a short period of time, whereas, less intense energy releases it energy gradually over a long period of time.
Answer: Both cannonballs will hit the ground at the same time.
Explanation:
Suppose that a given object is on the air. The only force acting on the object (if we ignore air friction and such) will be the gravitational force.
then the acceleration equation is only on the vertical axis, and can be written as:
a(t) = -(9.8 m/s^2)
Now, to get the vertical velocity equation, we need to integrate over time.
v(t) = -(9.8 m/s^2)*t + v0
Where v0 is the initial velocity of the object in the vertical axis.
if the object is dropped (or it only has initial velocity on the horizontal axis) then v0 = 0m/s
and:
v(t) = -(9.8 m/s^2)*t
Now, if two objects are initially at the same height (both cannonballs start 1 m above the ground)
And both objects have the same vertical velocity, we can conclude that both objects will hit the ground at the same time.
You can notice that the fact that one ball is fired horizontally and the other is only dropped does not affect this, because we only analyze the vertical problem, not the horizontal one. (This is something useful to remember, we can separate the vertical and horizontal movement in these type of problems)
