VERY EASY QUESTION FOR HIGH SCHOOL STUDENTS:

A force F of magnitude 2x^3 is applied to stop a particle moving with an initial velocity of v0. The particle travels from x=0 t

3241004551 [841]

Answer:

Explanation:

Given that

F=2x³

Work is given as

The range of x is from x=0 to x=D

W=-∫f(x)dx

Then,

W=-∫2x³dx from x=0 to x=D

W=- 2x⁴/4 from x=0 to x=D

W=-2(D⁴/4-0/4)

W=-D⁴/2

W=1/2D⁴

The correct answer is F

5 0

3 years ago

A flat coil having 160 turns, each with an area of 0.20 m 2, is placed with the plane of its area perpendicular to a magnetic fi

S_A_V [24]

Answer:

10.2 Watt

Explanation:

$N$ = number of turns in flat coil = 160

$A$ = area = 0.20 m²

B₀= initial magnetic field = 0.40 T

$B$ = final magnetic field = - 0.40 T

Change in magnetic field is given as

ΔB = B - B₀ = - 0.40 - 0.40 = - 0.80 T

$t$ = time taken for the magnetic field to change = 2.0 s

Induced emf is given as

$E = \frac{- N A \Delta B}{t}$

$E = \frac{- (160) (0.20) (- 0.80)}{2}$

$E$ = 12.8 volts

$R$ = Resistance of the coil = 16 Ω

Power is given as

$P = \frac{E^{2}}{R}$

$P = \frac{(12.8)^{2}}{16}$

$P$ = 10.2 Watt

6 0

3 years ago

A 2.0 m tall person is standing in front of a flat vertical mirror. What minimum height must the mirror have if the person is to

dangina [55]

Answer:

100cm

Explanation:

Since the eyes are 6 cm below the top of her head, the point of incidence of the ray must be

200cm-3cm=197cm

Since the eyes are 194 cm from her feet, the point of incidence of this ray must be

194cm/2=97cm

So the lower edge of the mirror must be 97 cm from the ground and the vertical dimension of the mirror must be 197 cm - 97 cm = 100 cm, which is half the height of the person.

7 0

3 years ago

There are competitions in which pilots fly small planes low over the ground and drop weights, trying to hit a target. Part A A p

tamaranim1 [39]

Explanation:

A pilot flying a weight; it takes t = 3.4 s to hit the ground, during which it travels a horizontal distance d = 120 m

h = g/2*t^2

h= 4.903*3.4^2

h=56.701 m

V = d/t

V= 120/3.4

V=35.3 m/sec

Now the pilot does a run at the same height but twice the speed.

How much time (t1) does it take the weight to hit the ground?

t1 = t = 3.4 sec (depending just upon height)

5 0

3 years ago

A calorimeter contained 350.0 g of water [cp=4.18 J/(g °C)] at 24.0 °C. An electric current was passed through a heater placed i

Shtirlitz [24]

Cp shows the amount of energy needed to raise temperature by one degree for one gram of water.

Formula for calculating cp is:
$cp= \frac{energy}{(mass)*( temperature_{change} ))} \\ temperature_{change}= \frac{energy}{(mass)*( cp))} \\ \\ temperature_{change}= \frac{16700}{(350)*( 4.18))} \\ \\ temperature_{change}=2.73 \\ \\ temperature_{final} =temperature_{initial}+temperature_{change} \\ temperature_{final}=24 + 2.73 \\ temperature_{final}=26.73$

Final temperature is 26.73°C.

4 0

3 years ago