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N76 [4]
3 years ago
7

The objective lens in a DVD player must move quickly to keep the laser beam focused on the disc's reflective layer. Why must thi

s lens have a very small mass?
Physics
1 answer:
Zinaida [17]3 years ago
4 0

Explanation:

The small mass of lens in a DVD player accounts for small inertia of the lens. Hence, even on application of force of small magnitude, the lens is rapidly accelerated. Moreover, the small mass of lens also accounts for lower resistance to change in its motion and therefore, again can be rapidly accelerated back and forth.

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To determine the height of a flagpole, Abby throws a ball straight up and times it. She sees that the ball goes by the top of th
Kryger [21]

Answer:

H = 10.05 m

Explanation:

If the stone will reach the top position of flag pole at t = 0.5 s and t = 4.1 s

so here the total time of the motion above the top point of pole is given as

\Delta t = 4.1 - 0.5 = 3.6 s

now we have

\Delta t = \frac{2v}{g}

3.6 = \frac{2v}{9.8}

v = 17.64 m/s

so this is the speed at the top of flag pole

now we have

v_f - v_i = at

17.64 - v_i = (-9.8)(0.5)

v_i = 22.5 m/s

now the height of flag pole is given as

H = \frac{v_f + v_i}{2}t

H = \frac{22.5 + 17.64}{2} (0.5)

H = 10.05 m

5 0
2 years ago
In which direction should you look to see the setting moon.
Virty [35]
Every sky object sets in the west.
3 0
3 years ago
Read 2 more answers
A 65.0 kg football player is running at 10.0 m/s downfield when he catches a 0.420 kg football thrown in the same direction but
lukranit [14]

Explanation:

Below is an attachment containing the solution.

8 0
3 years ago
A scooter is traveling at a constant speed v when it encounters a circular hill of radius r = 480 m. The driver and scooter toge
Grace [21]

Answer:

68.585m/sec , 779.1 N

Explanation:

To feel weightless, centripetal acceleration must equal g (9.8m/sec^2). The accelerations then cancel.

From centripetal motion.

F =( mv^2)/2

But since we are dealing with weightlessness

r = 480m

g = 9.8m/s^2

M also cancels, so forget M.

V^2 = Fr

V = √ Fr

V =√ (9.8 x 480) = 4704

= 68.585m/sec.

b) Centripetal acceleration = (v^2/2r) = (68.585^2/960) = 4704/960

= 4.9m/sec^2.

Weight (force) = (mass x acceleration) = 159kg x (g - 4.9)

159kg × ( 9.8-4.9)

159kg × 4.9

= 779.1N

6 0
3 years ago
Thermal energy is added to a sample, its particles move ?
8_murik_8 [283]
Yes, if the temperature increases, than that means the particles are moving faster. Temperature is the measure of movement of particles in an object or substance.

By thermal energy, you mean adding heat correct....? I'm not very good at this sort of thing, but I gave you what I have..
4 0
3 years ago
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