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3 years ago

What important characteristics of planets and moon are studied by astronomers?

Physics

1 answer:

kondor19780726 [428]3 years ago

5 0

mass density orbit time temperature surface conditions

distyance from sun

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A 30-kg child stands at one end of a floating 20-kg canoe that is 5.0-m long and initially at rest in the water. The child then

Yuliya22 [10]

Answer:

The canoe move 3 m in water.

Explanation:

Given that,

Mass of the child, m = 30 kg

Mass of canoe, M = 20 kg

Length of canoe, L = 5 m

Since initially the boat is floating, its center of mass was at rest. So, when child moves on the boat from one end to the other end, the boat moves in opposite direction in such a way that the displacement of their center of mass remains at rest.
Let x be the displacement of canoe in opposite direction to the motion of child, therefore displacement of child is L - x

So, the displacement of the center of mass is given by :

$d_{cm}=\dfrac{m(L-x)-Mx}{m+M}\\\\0=\dfrac{m(L-x)-Mx}{m+M}\\\\m(L-x)-Mx=0\\\\30(5-x)-20x=0\\\\x=3\ m$

So, the canoe move 3 m in water.

5 0

3 years ago

Name one non-metal that is a good conductor and why??

Vesna [10]

Answer:

silver

Explanation:

It is because it contains a higher number of movable atoms ( free electrons)

6 0

2 years ago

Now in "real life," this automobile is cruising at 20.5 m/s (equal to 73.8 km/hr) when it is about to hit a pedestrian stuck in

algol13

Answer:

He needs 1.53 seconds to stop the car.

Explanation:

Let the mass of the car is 1500 kg

Speed of the car, v = 20.5 m/s

He will not push the car with a force greater than, $F=2\times 10^4\ N$

The impulse delivered to the object is given by the change in momentum as :

$F\times t=mv\\\\t=\dfrac{mv}{F}\\\\t=\dfrac{1500\times 20.5}{2\times 10^4}\\\\t=1.53\ s$

So, he needs 1.53 seconds to stop the car. Hence, this is the required solution.

5 0

3 years ago

A 5 kg brick is dropped from a height of 12m on a spring with a spring constant 8 kN/m. If the spring has unstretched length of

Ivan

Answer:

0.1164 m

0.49387 m

Explanation:

m = Mass = 5 kg

g = Acceleration due to gravity = 9.81 m/s²

h = Height from which brick falls = 12 m

k = Spring constant = 8 kN/m

a) Potential energy of the brick

$PE=mgh\\\Rightarrow PE=5\times 9.81\times 12\\\Rightarrow PE=588.6\ J$

Potential energy in spring

$PE=\frac{1}{2}\times kx^2\\\Rightarrow x=\sqrt{\frac{PE\times 2}{k}}\\\Rightarrow x=\sqrt{\frac{588.6\times 2}{8000}}\\\Rightarrow x=0.3836\ m$

The compression of spring = 0.5-0.3836 = 0.1164 m

b) Weight of the brick

$F=5\times 9.81\\\Rightarrow F=49.05\ N$

$F=kx\\\Rightarrow x=\frac{F}{k}\\\Rightarrow x=\frac{49.05}{8000}\\\Rightarrow x=0.00613\ m$

The final length of the spring = 0.5-0.00613 = 0.49387 m

4 0

3 years ago

How is urine produced

Tom [10]

Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra.

5 0

3 years ago

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