Answer:
》How can a camera help someone see something he or she wouldn't normally be able to see?
- Although the human eye is able to observe fast events as they happen, it is not able to focus on a single point of time. We cannot freeze motion with our eyes. With a camera, however, so long as there is enough light, we can freeze motion. ... The camera can capture 'the moment', while your eye cannot.
》In what way is laser different from light produced by other sources?
-The major difference between laser light and light generated by white light sources (such as a light bulb) is that laser light is monochromatic, directional and coherent. ... Light from a conventional sources, such as a light bulb diverges, spreading in all directions.
Answer:
3. 3.5 s
Explanation:
The position of traveller A is given by the equation:
![x_A(t) = \frac{1}{2}a t^2](https://tex.z-dn.net/?f=x_A%28t%29%20%3D%20%5Cfrac%7B1%7D%7B2%7Da%20t%5E2)
where
is the acceleration of A
t is the time measured from when A started the motion
The position of traveller B instead is given by
![x_B(t) = u_B (t-2) + \frac{1}{2}a(t-2)^2](https://tex.z-dn.net/?f=x_B%28t%29%20%3D%20u_B%20%28t-2%29%20%2B%20%5Cfrac%7B1%7D%7B2%7Da%28t-2%29%5E2)
where a (acceleration) is the same as traveller A, and
![u_B = 20 m/s](https://tex.z-dn.net/?f=u_B%20%3D%2020%20m%2Fs)
is B's initial velocity. We can verify that the formula is correct by substituting t=2, and we get
, which means that B starts its motion 2 seconds later.
Traveller B overtakes traveller A when the two positions are the same, so:
![x_A = x_B\\\frac{1}{2}at^2 = u_B (t-2) + \frac{1}{2}a(t-2)^2\\\frac{1}{2}at^2 = u_B t - 2u_B +\frac{1}{2}at^2 +2a-2at\\u_Bt-2at = 2u_B-2a\\t=\frac{2u_B-2a}{u_B-2a}=\frac{2(20)-2(6)}{20-2(6)}=3.5 s](https://tex.z-dn.net/?f=x_A%20%3D%20x_B%5C%5C%5Cfrac%7B1%7D%7B2%7Dat%5E2%20%3D%20u_B%20%28t-2%29%20%2B%20%5Cfrac%7B1%7D%7B2%7Da%28t-2%29%5E2%5C%5C%5Cfrac%7B1%7D%7B2%7Dat%5E2%20%3D%20u_B%20t%20-%202u_B%20%2B%5Cfrac%7B1%7D%7B2%7Dat%5E2%20%2B2a-2at%5C%5Cu_Bt-2at%20%3D%202u_B-2a%5C%5Ct%3D%5Cfrac%7B2u_B-2a%7D%7Bu_B-2a%7D%3D%5Cfrac%7B2%2820%29-2%286%29%7D%7B20-2%286%29%7D%3D3.5%20s)
Lever: a bar used to move something
Wedge: a tool used to go in between object to put them in place
Incline plane : a ramp it’s used to help rise heavy things
Pulley: it’s a wheel that supports movement and change of direction
<span>the answer is energy is not created nor destroyed, but it can change from one energy form to another.</span>
The acceleration due to gravity on Earth is 9.8 m/s per second.