. What is the atomic number for calcium?

How will the motion of the arrow change after it leaves the bow?

alexira [117]

Answer:

depends on wind

Explanation:

epi

8 0

4 years ago

Jack and Jill are maneuvering a 3300 kg boat near a dock. Initially the boat's position is < 2, 0, 3 > m and its speed is

Paraphin [41]

Answer:

The workdone by Jack is $W_{jack} = -1050J$

The workdone by Jill is $W_{Jill} = 0J$

The final velocity is $v = 1.36 m/s$

Explanation:

From the question we are given that

The mass of the boat is $m_b = 3300kg$

The initial position of the boat is $P_i = (2 \r i + 0 \r j + 3\r k)m$

The Final position of the boat is $P_f = (4\r i + 0 \r j + 2\r k )\ m$

The Force exerted by Jack $\r F = (-420\r i + 0 \r j + 210\r k) \ N$

The Force exerted by Jill $\r F_{Jill} =(180 \r i + 0\r j + 360\r k)$

Now to obtain the displacement made we are to subtract the final position from the initial position

$\r P = P_f - P_i$

$= (4\r i + 0\r j + 2 \r k) - (2\r i + 0\r j + 3\r k )$

$= (2\r i + 0\r j -\r k )m$

Now that we have obtained the displacement we can obtain the Workdone

which is mathematically represented as

$W =\r F * \r P$

The amount of workdone by jack would be

$W_{jack} =\r F * \r P$

$= [(-420\r i +0\r j +210\r k)(2\r i + 0\r j - \r k)]$

$= (-420) (2) + (210)(-1)$

$= -840 - 210$

$=-1050J$

The amount of workdone by Jill would be

$W_{Jill} =\r F * \r P$

$= [(180 \r i + 0\r j + 360\r k)(2\r i +0\r j -\r k)]$

$= (180 )(2) +(360)(-1)$

$=0J$

According to work energy theorem the Workdone is equal to the kinetic energy of the boat

$W = K.E = \frac{1}{2} m *[v^2 - (1.1)^2]$

$-1050 = 0.5*3300 [*v^2- (1.1)^2]$

$-1050 = 1650 [v^2 -1.21]$

$0.6363 = v^2 -1.21$

$v^2 = 0.6363+1.21$

$v^2 =1.846$

$v = 1.36\ m/s$

6 0

4 years ago

What is the input of energy for a device that provides 50 units of useful energy and has an efficiency of 0.55?

marshall27 [118]

If that's the case, then

      50 units = 0.55 x the input energy

Divide each side by 0.55 :

   50 units/0.55 = the input energy =

   <em> 90 and 10/11 units</em>

3 0

4 years ago

A 0.3-kg ball has the velocity of 20 m/s. what is the kinetic energy of the ball?

snow_tiger [21]

Answer:

60 J

Explanation:

KE = ½ mv²

KE = ½ (0.3 kg) (20 m/s)²

KE = 60 J

7 0

3 years ago

Why must the difference between the water level in the eudiometer tube and the water level in the beaker be measured

Bas_tet [7]

Answer:

Explanation:

The difference between the water level in the eudiometer tube and the water level in the beaker must be measured because we have to put into consideration, the pressure of the gases in the eudiometer tube. This said pressure of gas in the eudiometer must equal the atmospheric pressure. If or by chance, the water levels happens not to be at the same height, then this is not the case. And then, as a result, in order to account for the difference between both, while also being able to get accurate results, you have to find the difference or subtract the water levels and then go ahead in converting them to mmHg.

3 0

3 years ago