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3 years ago

13

Given the displacement vector D = (4î − 8ĵ) m, find the displacement vector R (in m) so that D + R = −3Dĵ. (Express your answer

in vector form.)

1 answer:

Elena-2011 [213]3 years ago

4 0

Answer:

--------------------------------

Explanation:

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Ahab has been sent to the shops by his mother. The shops are 1200 m from his

Iteru [2.4K]

Answer:

it will take him 200secs to run to the shops

(btw 200 seconds is 3minutes and 20secs)

Explanation:

distance = speed x time

time = distance / speed

1200 ÷ 6 = 200

time = 200seconds

hope this helps

brainliest please?

x

8 0

3 years ago

In each case, lifting or pushing, why must you exert a force to move the object? Q1-2: How much more effort is required to lift

musickatia [10]

Answer:

Newton's first law applies. An object at rest will stay that way until a force is applied.
Any amount of effort can be applied to any amount of mass (in the ideal case). The question is not sufficiently specific.

Explanation:

A force is required to move an object because the object will stay at rest until a force is applied.

__

The effort required to lift or push two masses instead of one depends on the desired effect. For the same kinetic energy, no more effort is required. For the same momentum, half the effort is required for two masses. For the same velocity, double the effort is required.

4 0

3 years ago

The Kentucky Derby is held at the Churchill Downs track in Louisville, Kentucky. The track is one and one-quarter miles in lengt

Lera25 [3.4K]

Answer:

2.815 seconds

Explanation:

t = Time taken

u = Initial velocity

v = Final velocity

s = Displacement

a = Acceleration

$s=ut+\frac{1}{2}at^2\\\Rightarrow 1609.34=16.58\times t+\frac{1}{2}\times 0.0105\times t^2\\\Rightarrow \\\Rightarrow 4.905t^2+16.58t-1609.34=0$

$t=\frac{-16.58+\sqrt{308.69254}}{0.0105},\:t=\frac{-16.58-\sqrt{308.69254}}{0.0105}\\\Rightarrow t=94.25, -3252\ s$

Time taken with the acceleration is 94.25 seconds

Time = Distance / Speed

$\text{Time}=\frac{1609.34}{16.58}\\\Rightarrow \text{Time}=97.065\ s$

Difference in time = 97.065-94.25 = 2.815 seconds

6 0

3 years ago

0.180-kg stone rets on a frictionless, horizontal surface. A bullet of mass 7.50 g, traveling horizontally at 390 m/s, strikes t

Musya8 [376]

Answer:

The magnitud of the velocity is

$8.46m/s$

and the direccion:

$-28.3$ degrees from the horizontal.

Explanation:

Fist we define our variables:

$m_{s}=0.18kg\\m_{b}=7.5g = 0.0075kg\\v_{1b}= 390m/s -i\\v_{1s}=0m/s\\v_{2b}=210m/s -j\\v_{2s}=?$

The letters i and j represent the direction of the movement, i in this case is the horizontal direction, and j is perpendicular to i.

velocities with sub-index 1 are the speeds before the crash, and with sub-index 2 are the velocities after the crash.

Using conservation of momentum:

$m_{s}v_{1s}+m_{b}v_{1b}=m_{s}v_{2s}+m_{b}v_{2b}\\v_{1s}=0, so\\m_{b}v_{1b}=m_{s}v_{2s}+m_{b}v_{2b}$

Clearing for the velocity of the stone after the crash:

$v_{2s}=\frac{m_{b}v_{1b}-m_{b}v_{2b}}{m_{s}}$

Substituting known values:

$v_{2s}=\frac{0.0075kg(((390m/s-i)-210m/s-j)}{0.18kg}\\v_{2s}=(16.25m/s-i) - (8.75m/s-j)$

The magnitud of the velocity is :

$|v_{2s}|=\sqrt{(16.25m/s-i)^2 + (8.75m/s-j)^2}\\|v_{2s}|=18.46m/s$

and the direction:

$tan^{-1}(-8.75/16.25)=-28.3$

this is -28.3 degrees from the +i direction or the horizontal direcction.

Note: i and j can also be seen as x and y axis.

3 0

3 years ago

10. A car starts from rest at a stop light and reaches 20 m/s in 3.5

liq [111]

B i believe not really sure but that math i did seems about right

3 0

3 years ago

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