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Citrus2011 [14]
3 years ago
14

You are pushing a wooden crate across the floor at constant speed. You decide to turn the crate on end, reducing by half the sur

face area in contact with the floor. In the new orientation, to push the same crate across the same floor with the same speed, the force that you apply must be aboutA. Four times as greatB. Twice as greatC. Equally greatD. Half as greatE. One-fourth as greatas the force required before you changed the crate's orientation.
Physics
1 answer:
borishaifa [10]3 years ago
3 0

Answer:

D. Half as great

Explanation:

Since we know that the friction force between the surface of crate and ground is given as

F_f = \mu F_n

so here we know that

\mu = friction coefficient between two surfaces which depends on the effective contact area between two surfaces

F_n = normal force due to the object

So when we turn the object on another side such that the surface area is half then the friction coefficient will become also half

So here the friction force will also reduce to half

so correct answer will be

D. Half as great

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An astronaut drops a rock from the top of a crater on the moon. When the rock is halfway down to the bottom of the crater, its s
Alexxx [7]

Answer: vf1/vf2= 1/ sqrt(2)

Explanation :on the moon no drag force so we have only the  force of gravity. aceleration is g(moon)= 1.62m/s2.the rest is basic kinematics

if the rock travels H to the bottom we can calculate velocity:

vo=0m/s (drops the rock)  , yo=0

vf*vf= vo*vo+2g(y-yo)

when the rock is halfway  y = H/2 so:

vf1*vf1=2*g*H/2 so vf1 = sqrt(gH)

when the rock reach the bottom y=H so:

vf2*vf2=2*g*H so vf2 = sqrt(2gH)

so vf1/vf2= 1/ sqrt(2)

good luck from colombia

8 0
3 years ago
Read 2 more answers
When a current flows in an aluminum wire of diameter 2.91 mm 2.91 mm , the drift speed of the conduction electrons is 0.000191 m
charle [14.2K]

Answer:

Number of electrons are flowing per second is 2.42 x 10¹⁹

Explanation:

The electric current flows through a wire is given by the relation :

I=envA   ....(1)

Here I is current, e is electronic charge, v is drift velocity of electrons and A is the Area of the wire.

But electric current is also define as rate of electrons passing through junction times their charge, i.e. ,

I=Ne      ....(2)

Here N is the rate of electrons passing through junction.

From equation (1) and (2).

eN = envA

N=nvA

But area of wire, A=\pi \frac{d^{2} }{4}

Here d is diameter of wire.

So, N = nv\pi \frac{d^{2} }{4}

Substitute 2.91 x 10⁻³ m for d, 0.000191 m/s for v and 6 x 10²⁸ m⁻³ for n in the above equation.

N = 6\times10^{28}\times 0.000191\times\pi \frac{(2.91\times10^{-3} )^{2} }{4}

N = 2.42 x 10¹⁹ s⁻¹  

8 0
3 years ago
Based on the graph, describe how momentum changes with time for an object in free fall. If you can help, I would be so grateful.
pochemuha
With time, momentum increases as it builds speed assuming their is nothing in the way to stop it. Based on the graph, you can see that example being displayed as the line on the graph gets higher
4 0
3 years ago
how fast is a ball going when it hits the ground after being dropped from a height of 16m the acceleration of gravity is 9.8
Aneli [31]

Answer:

17.7 m/s

Explanation:

Given:

y₀ = 0 m

y = 16 m

v₀ = 0 m/s

a = 9.8 m/s²

Find: v

v² = v₀² + 2a (y − y₀)

v² = (0 m/s)² + 2 (9.8 m/s²) (16 m − 0 m)

v = 17.7 m/s

The ball is moving at a speed of 17.7 m/s when it hits the ground.

8 0
3 years ago
Beats are the difference in (a) Frequency (b) Amplitude (c) Intensity (d) None
sasho [114]

Answer:

Beats are the difference in frequency.

(a) is correct option.

Explanation:

Beat :

Beat is the difference of the frequency of two waves.

The difference in frequency is equal to the number of beat per second.

Amplitude :

Amplitude of the wave is the maximum displacement.

Frequency :

Frequency is the number oscillations of wave in per second.

Intensity :

Intensity is the power per unit area.

Hence, Beats are the difference in frequency.

7 0
3 years ago
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