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erastovalidia [21]
4 years ago
8

The force pressing two stacked objects together is equal to the weight of the object on top. The friction between a piece of woo

d on a stone surface is 22.5 newtons. The same piece of wood is placed on another surface, and the friction between the wood and the surface is now 46.5 newtons.
What could be the second surface?

A) metal
B) concrete
C) brick
D) skin
Physics
1 answer:
34kurt4 years ago
3 0

Answer: B. Concrete

Explanation:

Let N = reacting force pressing the bodies in context together (units in Newtons),

The question stated that the force pressing the two mounted/stacked objects together is equal to the weight of the object on top.

We need to start by finding the weight of the piece of wood.

friction is given by

f = μN

The value of f is 22.5,

and from the chart reference the coefficient of friction between wood and stone, μ is 0.30.

22.5 = 75. 0.30

Putting the values into the equation: 22.5 = 0.30N.

Divide both sides by 0.30 to find the value of N:

N= 22.5/0.3 = 75

Now that the piece of wood will be placed on another surface, its weight of 75 Newton is the force pressing the two bodies together.

To determine the new surface, you should find the new coefficient of friction by using the new value of the force of friction given 46.5:

46.5 = µ(75).

Divide both sides by 75 to isolate μ.

The refer chart also indicates that the coefficient of friction equals 0.62 between wood and concrete, so the new surface corresponding to 0.62 is the concrete, which is (B).

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a golfer hits a golf ball giving it an initial velocity 30m/s at an angle 45° from the horizontal. ignoring air resistance on a
Lynna [10]

Answer:

90 meters.

Explanation:

The correct answer is: B.) 90 m

4 0
3 years ago
A 40 kg slab rests on a frictionless floor. A 10 kg block rests on top of the slab. The coefficient of static friction between t
Wewaii [24]

Answer:

a) a = 6.1 m/s^2

b)  a = 0.98m/s^2

Explanation:

Mass of slab = 40kg

Mass of block = 10kg

Coefficient of static friction (Us)  = 0.60

Kinetic coefficient (UK)  = 0.40

Horizontal force = 100N

The normal reaction from 40kg slab on 10 kg block = 10*9.81

= 98.1N

Static frictional force = Us*R

= 98.1*0.6

= 58.86N

This is less than the force applied

If 10 kg block will slide on the 40 kg slab,  net force = 100 - kinetic force

Kinetic force (Uk*R) = 0.4*98.1

= 39.28N

= 39N

Net force = 100 -39

= 61N

Recall that F = ma

For 10 kg block

a = F/m

a = 61/10

a = 6.1m/s^2

b) Frictional force on 40 kg slab by 10 kg = 98.1*0.4

= 39.24

= 39N

F = ma

a = F/m

For 40kg slab

a = 39/40

a = 0.98m/s^2

3 0
3 years ago
If a trapeze artist rotates once each second while sailing through the air, and contracts to reduce her rotational inertia to on
finlep [7]

Answer:

There are finally 4 rotations per second.

Explanation:

If a trapeze artist rotates once each second while sailing through the air, and contracts to reduce her rotational inertia to one fourth of what it was. We need to find the final angular velocity. It is a case of conservation of angular momentum such that :

I_1\omega_1=I_2\omega_2

Let I_1=I , I_2=\dfrac{I}{4} and \omega_1=1

So,

\omega_2=\dfrac{I_1\omega_1}{I_2}

\omega_2=\dfrac{I\times 1}{(I/4)}

\omega_2=4\ rev/sec

So, there are finally 4 rotations per second. Hence, this is the required solution.

4 0
3 years ago
Which of the following materials offer the least electrical resistance? Pure water, wood, salt water, glass
Vanyuwa [196]

Salt water offers the least electrical resistance.

<u>Explanation:</u>

Least electrical resistance indicates that any material which readily allows the electric current through itself, and shows more conductivity.

Here pure water doesn't contain any ions, so it is a bad conductor.

Wood and glass are also bad conductors of electricity.

Salt water contains ions, which conducts electricity which means it shows least electrical resistance.

5 0
4 years ago
Georgie was pulling her brother (of mass 16 kg) in a 9.4 kg sled with a constant force of 39 N for one block (128 m). How much w
Genrish500 [490]

Answer:

4992 J

Explanation:

Force, F = 39 N

Distance, s = 128 m

Work done = force x distance

W = 39 x 128

W = 4992 J

Thus, the work done is 4992 J.

7 0
3 years ago
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