3. Which is an example of a safe laboratory procedure?

Si el número masico del elemento litio es 7 ¿cual es su nucleo?

sp2606 [1]

El núcleo tiene 3 protones (lo que le da al núcleo una carga de +3, identificándolo como el elemento Litio) y 4 neutrones (lo que le da un número total de masa de 7).

4 0

3 years ago

011 10.0 points

Ulleksa [173]

Answer:

2.47 m

Explanation:

Let's calculate first the time it takes for the ball to cover the horizontal distance that separates the starting point from the crossbar of d = 52 m.

The horizontal velocity of the ball is constant:

$v_x = v cos \theta = (25)(cos 35.9^{\circ})=20.3 m/s$

and the time taken to cover the horizontal distance d is

$t=\frac{d}{v_x}=\frac{52}{20.3}=2.56 s$

So this is the time the ball takes to reach the horizontal position of the crossbar.

The vertical position of the ball at time t is given by

$y=u_y t - \frac{1}{2}gt^2$

where

$u_y = v sin \theta =(25)(sin 35.9^{\circ})=14.7 m/s$ is the initial vertical velocity

g = 9.8 m/s^2 is the acceleration of gravity

And substituting t = 2.56 s, we find the vertical position of the ball when it is above the crossbar:

$y=(14.7)(2.56) - \frac{1}{2}(9.8)(2.56)^2=5.52 m$

The height of the crossbar is h = 3.05 m, so the ball passes

$h' = 5.52- 3.05 = 2.47 m$

above the crossbar.

8 0

3 years ago

Determine the rate at which the electric field changes between the round plates of a capacitor, 8.0 cm in diameter, if the plate

Daniel [21]

Solution:

The relation between the potential difference and the electric field between the plates of the parallel plate capacitor is given by :

$E=\frac{V}{D}$

Differentiating on both the sides with respect to time, we get

$\frac{dE}{dt}=\frac{1}{D}\frac{dV}{dt}$

Therefore, the rate of the electric field changes between the plates of the parallel plate capacitor is given by :

$\frac{dE}{dt}=\frac{1}{D}\frac{dV}{dt}$

$=\frac{1}{1.4 \times 10^{-3}} \times 110$

$=7.85 \times 10^4$ V/m-s

8 0

3 years ago

What is the difference between revolution and rotation

Sphinxa [80]

A rotation is when the earth turns in a circle on it's axis. A revolution is the oblong path the the earth is constantly moving in around the sun. A revolution takes 365.25 days where as a rotation happens in 24 hours. <span />

8 0

3 years ago

Read 2 more answers

The captain of a boat wants to travel directly across a river that flows due exst with a speed of 100 m/sHe starts from the sout

Salsk061 [2.6K]

Answer:

86.51° North of West or 273.49°

Explanation:

Let V' = velocity of boat relative to the earth, v = velocity of boat relative to water and V = velocity of water.

Now, by vector addition V' = V + v'.

Since v' = 6.10 m/s in the north direction, v' = (6.10 m/s)j and V = 100 m/s in the east direction, V = (100 m/s)i. So that

V' = V + v'

V' = (100 m/s)i + (6.10 m/s)j

So, we find the direction,Ф the boat must steer to from the components of V'.

So tanФ = 6.10 m/s ÷ 100 m/s

tanФ = 0.061

Ф = tan⁻¹(0.061) = 3.49°

So, the angle from the north is thus 90° - 3.49° = 86.51° North of West or 270° + 3.49° = 273.49°

7 0

3 years ago