4. Magnets with one pole are now routinely made.<br> True or False

An electric toy with a resistance of 2.50 Ω is operated by a 3.00-V battery. (a) What current does the toy draw? (b) Assuming th

Leno4ka [110]

Answer:

a) The current is i = 1.2 A

b) The charge is Q = 17280 C

c) The energy is E = 43200 J

Explanation:

a) The current is given by the ohm's law wich is:

i = V/R = 3/2.5 = 1.2 A

b) Since the charge is steady we can use the following equation to find the charge amount in that time:

i = Q/t

Q = t*i

Where t is in seconds, so we have 4h * 3600 = 14400 s

Q = 1.2*14400 = 17280 C

c) The energy is the power delivered to the toy multiplied by the time:

P = 1.2*2.5 = 3 W

E = P*t = 3*14400 = 43200 J

7 0

3 years ago

If you were to drop a rock from a tall building, assuming that it had not yet hit the ground, and neglecting air resistance. Wha

Olegator [25]

Answer:

Explanation:

Using the equation of motion S = ut + 1/2 gt²

S = the vertical displacement (in m)

u = initial velocity of the object (in m/s)

g = acceleration due to gravity (in m/s²)

t = time taken (in secs)

Given u = 0m/s, g = 10m/s² and t = 10s, substituting this value into the equation to get the vertical displacement w have;

S = 0+1/2 (10)(10)²

S = 1000/2

S = 500m

The vertical displacement after 10seconds is 500m

5 0

3 years ago

A dog pulls on a pillow with a force of 5 N at an angle of 37o to the horizontal. Find the x and y components of this force.

Paha777 [63]

Answer:

$x=3.99\ N\approx4\ N$

$y=3\ N$

Explanation:

Given :

Force with which dog pulls the pillow = 5 N

Angle of force to the horizontal = 37°

To find the $x$ and $y$ components of force.

Solution:

For a force $F$ making an angle $\theta$ with the horizontal, the

1) $x$ component or the horizontal component is given by:

$x=F\cos\theta$

2) $y$ component or the vertical component is given by:

$y=F\sin\theta$

Plugging the know values to find $x$ and $y$ components of force applied by the dog on pillow

1) $x=5\cos37\°$

∴ $x=3.99\ N\approx4\ N$ (Answer)

2) $y=5\sin37\°$

∴ $y=3\ N$ (Answer)

7 0

3 years ago

A moving curling stone, A, collides head on with stationary stone, B. Stone B has a larger mass than stone A. If friction is neg

Kitty [74]

Answer:

The correct answer is option 'c': Smaller stone rebounds while as larger stone remains stationary.

Explanation:

Let the velocity and the mass of the smaller stone be 'm' and 'v' respectively

and the mass of big rock be 'M'

Initial momentum of the system equals

$p_i=mv+0=mv$

Now let after the collision the small stone move with a velocity v' and the big roch move with a velocity V'

Thus the final momentum of the system is

$p_f=mv'+MV'$

Equating initial and the final momenta we get

$mv=mv'+MV'\\\\m(v-v')=MV'.....i$

Now since the surface is frictionless thus the energy is also conserved thus

$E_i=\frac{1}{2}mv^2$

Similarly the final energy becomes

$E_f=\frac{1}{2}mv'^2+\frac{1}{2}MV'^2$ \

Equating initial and final energies we get

$\frac{1}{2}mv^2=\frac{1}{2}mv'^2+\frac{1}{2}MV'^2\\\\mv^2=mv'^2+MV'^2\\\\m(v^2-v'^2)=MV'^2\\\\m(v-v')(v+v')=MV'^2......(ii)$

Solving i and ii we get

$v+v'=V'$

Using this in equation i we get

$v'=\frac{v(m-M)}{(M-m)}=-v$

Thus putting v = -v' in equation i we get V' = 0

This implies Smaller stone rebounds while as larger stone remains stationary.

4 0

3 years ago

Please help me on question 3a and 3b.<br><br>Thanks!

Sonbull [250]

(a) The frequency of water wave is 2 Hz.

(b) The wave speed of the water wave is 3.6 m/s.

<u>Explanation:</u>

(a) It is known that completion of one complete wave in 1 second is defined as frequency of 1 HZ. So here there are 120 waves crossing the boat in 1 minute. So the frequency of the water wave will be

$Frequency =\frac{\text { Number of waves }}{\text { Time in seconds }}$

As the time is 1 minute which is equal to 60 seconds and the number of waves is given as 120 then the frequency of the water wave is

$\text { Frequency }=\frac{120}{60}=2 \mathrm{Hz}$

So the frequency of water wave is 2 Hz.

(b) Then if the wavelength of the water wave is 1.8 m with a frequency of 2 Hz, then speed of the wave can be determined as the product of wavelength with frequency.

So Speed = Frequency × Wavelength

Speed = 2 × 1.8 = 3.6 m/s.

So the speed of the water wave is 3.6 m/s.

7 0

3 years ago

4. Magnets with one pole are now routinely made. True or False