_______is the resistance to motion offered by an object sliding over a surface

The dwarf planet Ceres contains over 50% of the mass of the main asteroid belt.

PolarNik [594]

False

Explanation:

Called an asteroid for many years, Ceres is so much bigger and so different from its rocky neighbors that scientists classified it as a dwarf planet in 2006. Even though Ceres comprises 25 percent of the asteroid belt's total mass, tiny Pluto is still 14 times more massive.

6 0

3 years ago

A 62-kg person jumps from a window to a fire net 20.0 m directly below, which stretches the net 1.4 m. Assume that the net behav

gayaneshka [121]

Answer:

a) x = 0.098

b) x = 2.72 m

Explanation:

(a) To find the stretch of the fire net when the same person is lying in it, you can assume that the net is like a spring with constant spring k. It is necessary to find k.

When the person is falling down he acquires a kinetic energy K, this energy is equal to the elastic potential energy of the net when it is max stretched.

Then, you have:

$K=U\\\\\frac{1}{2}mv^2=\frac{1}{2}kx^2$ (1)

m: mass of the person = 62kg

k: spring constant = ?

v: velocity of the person just when he touches the fire net = ?

x: elongation of the fire net = 1.4 m

Before the calculation of the spring constant, you calculate the final velocity of the person by using the following formula:

$v^2=v_o^2+2gy$

vo: initial velocity = 0 m/s

g: gravitational acceleration = 9.8 m/s^2

y: height from the person jumps = 20.0m

$v=\sqrt{2gy}=\sqrt{2(9.8m/s^2)(20.0m)}=14\frac{m}{s}$

With this value you can find the spring constant k from the equation (1):

$mv^2=kx^2\\\\k=\frac{mv^2}{x^2}=\frac{(62kg)(14m/s)^2}{(1.4m)^2}=6200\frac{N}{m}$

When the person is lying on the fire net the weight of the person is equal to the elastic force of the fire net:

$W=F_e\\\\mg=kx$

you solve the last expression for x:

$x=\frac{mg}{k}=\frac{(62kg)(9.8m/s^2)}{6200N/m}=0.098m$

When the person is lying on the fire net the elongation of the fire net is 0.098m

b) To find how much would the net stretch, If the person jumps from 38 m, you first calculate the final velocity of the person again:

$v=\sqrt{2gy}=\sqrt{2(9.8m/s^2)(38m)}=27.29\frac{m}{s}$

Next, you calculate x from the equation (1):

$x=\sqrt{\frac{mv^2}{k}}=\sqrt{\frac{(62kg)(27.29m/s)^2}{6200N/m}}\\\\x=2.72m$

The net fire is stretched 2.72 m

5 0

3 years ago

An uncharged conductor has a hollow cavity inside of it. Within this cavity there is a charge of +10 µC that does not touch the

aliina [53]

Answer:

Explanation:

we have to make charge inside the conductor zero because we know that electric field inside the conductor should be zero

so, the outer surface of the conductor should contain + 10 uC of charge and the inner surface contains -10 uC

8 0

3 years ago

A light year is defined as the distance that light can travel in 1 year. What is the value of 1 light year in meter? Show your c

Ipatiy [6.2K]

Answer:

d=9.462×10^15 meters

Explanation:

<u>Relation between distance, temps and velocity:</u>

d=v*t

t=1year*(365days/1year)*/(24hours/1day)*(3600s/1h)=31536000s

So:

1 light year=d=3*10^8m/s*3.154*10^7s=9.462×10^15 meters

6 0

3 years ago

A 50-g chunk of 80 degrees C iron is dropped into a cavity in a very large block of ice at 0 degrees C. Show that 5.5 g of ice w

Alenkasestr [34]

Answer:

5.5g of ice melts when a 50g chunk of iron at 80°C is dropped into a cavity

Explanation:

The concept to solve this problem is given by Energy Transferred, the equation is given by,

$Q = mc\Delta T$

Where,

Q= Energy transferred

m = mass of water

c = specific heat capacity

$\Delta T =$ Temperature change (K or °C)

Replacing the values where mass is 50g and temperature is 80°C to 0°C we have,

$Q = mc\Delta T$

$Q = 50*0.11*(80-0)$

$Q = 440cal$

Then we can calculate the heat absorbed by m grams of ice at 0°C, then

$Q_2 = mL = 80*m$

How Q_1=Q_2, so

$80m=440$

$m=\frac{440}{80}$

$m = 5.5g$

Then 5.5g of ice melts when a 50g chunk of iron at 80°C is dropped into a cavity

7 0

3 years ago