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2 years ago

Is the amount of friction greater between rough surfaces or smooth surfaces? Why?

Physics

1 answer:

nalin [4]2 years ago

6 0

Answer:

friction occurs because no surface is perfectly smooth.

Explanation:

rougher surfaces have more friction between them.

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Calculate the magnitude of the average gravitational force between earth and the moon

zepelin [54]

F = G mM / r^2, where
F = gravitational force between the earth and the moon, 
G = Universal gravitational constant = 6.67 x 10^(-11) Nm^2/(kg)^2, 
m = mass of the moon = 7.36 × 10^(22) kg 
M = mass of the earth = 5.9742 × 10^(24) and 
r = distance between the earth and the moon = 384,402 km 

F 
= 6.67 x 10^(-11) * (7.36 × 10^(22) * 5.9742 × 10^(24) / (384,402 )^2 
= 1.985 x 10^(26) N

5 0

2 years ago

A student connects a 1 hp motor to a bicycle. How much time will it take for the bicycle to accelerate from rest to a speed of 5

bija089 [108]

Answer:

t=2s

Explanation:

The definition of power is:

$P=\frac{W}{t}$

And the work-energy theorem states that:

$W=\Delta K$

Since the movement starts from rest, we have that:

$\Delta K=\frac{mv_f^2}{2}-\frac{mv_0^2}{2}=\frac{mv_f^2}{2}$

And putting all together:

$P=\frac{mv_f^2}{2t}$

Since we want the time taken:

$t=\frac{mv_f^2}{2P}$

Which for our values is:

$t=\frac{(120kg)(5m/s)^2}{2(746W)}=2s$

7 0

3 years ago

Read 2 more answers

a runner covers the last straight stretch of the race in 4 s. durning that time, he speeds up from 5 m/s to 9m/s what is the run

Sergio039 [100]

Answer:

The runner's acceleration was $1\ m/s^2$

Explanation:

Constant Acceleration Motion

It's a type of motion in which the velocity of an object changes by an equal amount in every equal period of time.

Being a the constant acceleration, vo the initial speed, vf the final speed, and t the time, the following relation applies:

$v_f=v_o+at$

Solving for a:

$\displaystyle a=\frac{v_f-v_o}{t}$

The runner speeds up from vo=5 m/s to vf=9 m/s in t=4 seconds, thus:

$\displaystyle a=\frac{9-5}{4}$

$\displaystyle a=\frac{4}{4}=1$

The runner's acceleration was $1\ m/s^2$

5 0

3 years ago

What is the speed of a car that travels 48 km in 2 hours?

ankoles [38]

Speed=distance/time

distance =48km
time=2 hours

speed=48/2
=24km/h

speed=24km/h

FORMULAS

speed = distance/time
time = distance/speed
distance = speed×time

3 0

3 years ago

Help! Il give brainlest to who answers first

Readme [11.4K]

Answer:

1. The density of the cube is 1.03 g/mL.

2. Dish soap

Explanation:

1. Determination of the density of the cube.

From the question given above, the following data were obtained:

Mass (m) of cube = 21.7 g

Volume (V) of cube = 21 mL

Density (D) of cube =?

The density of a substance is simply defined as the mass of the substance per unit volume of the substance. Thus, density can be expressed mathematically as:

Density (D) = mass (m) / volume (V)

D = m / V

With the above formula, we can obtain the density of the cube as follow:

Mass (m) of cube = 21.7 g

Volume (V) of cube = 21 mL

Density (D) of cube =?

D = m / V

D = 21.7 / 21

D = 1.03 g/mL

Thus, the density of the cube is 1.03 g/mL.

2. Determination of the layer of density the cube will settle in.

From the question given above,

Subtance >>>>>>>> Density

Vegetable oil >>>>> 0.91 g/mL

Grape juice >>>>>> 0.97 m/L

Water >>>>>>>>>>> 1 g/mL

Dish soap >>>>>>>> 1.03 g/mL

Maple syrup >>>>>> 1.37 g/mL

Comparing the density of the cube (i.e 1.03 g/mL) with those in the table able, we can conclude that the cube will settle in the DISH SOAP layer since they both have the same density.

7 0

2 years ago