The idea that "students ' immune systems have declined due to the use of hand sanitizers " is a hypothesis.
The term hypothesis refers to an intelligent guess or idea often based which is subject to scientific investigation via experiments.
A hypothesis may be right or wrong. We can only prove a hypothesis by subjecting it to a series of rigorous experiments.
Thus Collette's idea is a hypothesis.
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Answer:
H = 3.9 m
Explanation:
mass (m) = 48 kg
initial velocity (initial speed) (U) = 8.9 m/s
final velocity (V) = 1.6 m/s
acceleration due to gravity (g) = 9.8 m/s^{2}
find the height she raised her self to as she crosses the bar (H)
from energy conservation, the change in kinetic energy = change in potential energy
0.5m(V^{2} - [test]U^{2}[/tex]) = mg(H-h)
where h = initial height = 0 since she was on the ground
the equation becomes
0.5m(V^{2} - [test]U^{2}[/tex]) = mgH
0.5 x 48 x (1.6^{2} - [test]8.9^{2}[/tex]) = 48 x 9.8 x H
-1839.6 = 470.4 H (the negative sign indicates a decrease in kinetic energy so we would not be making use of it further)
H = 3.9 m
Answer:
The total amount of energy that would have been released if the asteroid hit earth = The kinetic energy of the asteroid = 1.29 × 10¹⁵ J = 1.29 PetaJoules = 1.29 PJ
1 PJ = 10¹⁵ J
Explanation:
Kinetic energy = mv²/2
velocity of the asteroid is given as 7.8 km/s = 7800 m/s
To obtain the mass, we get it from the specific gravity and diameter information given.
Density = specific gravity × 1000 = 3 × 1000 = 3000 kg/m³
But density = mass/volume
So, mass = density × volume.
Taking the informed assumption that the asteroid is a sphere,
Volume = 4πr³/3
Diameter = 30 m, r = D/2 = 15 m
Volume = 4π(15)³/3 = 14137.2 m³
Mass of the asteroid = density × volume = 3000 × 14137.2 = 42411501 kg = 4.24 × 10⁷ kg
Kinetic energy of the asteroid = mv²/2 = (4.24 × 10⁷)(7800²)/2 = 1.29 × 10¹⁵ J
Answer:
Its acceleration is positive
Explanation:
As the car is moving in the negative x-direction than after applying brake then there will be a decrease in the acceleration but in the opposite direction.
As decreasing acceleration consider to be negative but the car is moving in negative direction which means increasing acceleration is negative by sign convention but by applying brake acceleration decrease but in opposite direction than it will give positive value of acceleration.
Here we deal with a lever law. It states that product of force and distance from a fixed point on a lever is equal on both sides.
F₁*d₁ = F₂*d₂
By analysing this formula we can see that applying small force on a great length equals great force on a small length.
To remove nail we need to apply certain force. If we use F₁ for this required force we can see that on other side we need to apply certain force. If we have greater arm length we need smaller force. In a crowbar arm length along which we apply force is greater than length of our arm. This leads to a conclusion that we need smaller force when using crowbar. Depending on the length of a nail it is possible that we need to apply force that is greater than force required to remove nail.
