True: when there is an angle between force and displacement, 
Explanation:
The work done by a force when pushing/pulling an object is given by the equation
where
F is the magnitude of the force
d is the displacement of the object
is the angle between the direction of the force and of the displacement
We have two extreme cases:
- When the force is parallel to the displacement, then 
and 
, so the work done is maximum and simply becomes
- When the force is perpendicular to the displacement, then 
and 
, so the work done is zero.
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Answer:
Screaming is an emotional response triggered by the brain which receives information about the pain later as compared to pulling away of finger which is a reflex action facilitated by the spinal cord that has a quicker-time to response.
Explanation:
Reflex action happens when part of our body comes to contact with an object which can cause harm and you tend to quickly withdraw that part of the body.Reflex action happens quicker before the brain gets the time to process information about the harm.
When the baby touched the hot pan, at point of contact, skin receptors send nerve impulses to the spinal cord. Interneurons in the spinal cord relay a response to motor neurons to stimulate muscle contraction making the baby to pull his finger away.This happens so fast before the brain receives the message later to trigger emotional response(screaming).
Answer:
3.6×10⁶ m
Explanation:
Newton's law of universal gravitation states that the force between two masses is:
F = GMm / r²
where G is the universal constant of gravitation (6.67×10⁻¹¹ m³/kg/s²),
M is the mass of one object
m is the mass of the other object,
and r is the distance between the center of masses of the objects.
The force acting on the meteor is:
∑F = ma
GMm / r² = ma
GM / r² = a
Given M = 6×10²⁴ kg and a = 4 m/s²:
(6.67×10⁻¹¹ m³/kg/s²) (6×10²⁴ kg) / r² = 4 m/s²
r = 10⁷ m
The distance from the meteor to the center of the Earth is 10⁷ m. We want to know what the height of the meteor is (distance to the surface of the Earth). So we need to subtract the Earth's radius.
h = 10⁷ m − 6.4×10⁶ m
h = 3.6×10⁶ m
1. a) In order to sharpen the objective with a 40x objective (400x total magnification), the objective must be closer to the sample than with a 10x objective (100x total magnification), so the sample is out of focus.
b) At 400x total magnification, the field of view is narrower than at 100x total magnification.
c) A 40x objective (i.e. 400x total magnification) has a higher numerical aperture than a 10x objective (i.e. 100x total magnification) and therefore provides better resolution.
d) Shallow depth of field.
e) The amount of light is reduced.
f) Shorter working distance.
2. The best objective for observing bacteria is the 100x objective, which is the immersion objective.
3. Without the addition of immersion oil, the sample will look blurry and will not give maximum resolution.
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Answer:
The time elapsed at the spacecraft’s frame is less that the time elapsed at earth's frame
Explanation:
From the question we are told that
The distance between earth and Retah is 
Here c is the peed of light with value 
The time taken to reach Retah from earth is 
The velocity of the spacecraft is mathematically evaluated as
substituting values
The time elapsed in the spacecraft’s frame is mathematically evaluated as
substituting value
![T = 90000 * \sqrt{ 1 - \frac{[2.4*10^{8}]^2}{[3.0*10^{8}]^2} }](https://tex.z-dn.net/?f=T%20%20%3D%20%2090000%20%2A%20%20%5Csqrt%7B%201%20-%20%20%5Cfrac%7B%5B2.4%2A10%5E%7B8%7D%5D%5E2%7D%7B%5B3.0%2A10%5E%7B8%7D%5D%5E2%7D%20%7D)
=> 
So The time elapsed at the spacecraft’s frame is less that the time elapsed at earth's frame
