Download Task part 1

Part I. Density, pressure, buoyant force, statics
1.
What instrument is used to measure volume directly?
Variants of answer:
Measuring jar
Measuring tape
Thermometer
Stop watch
2.
Calculate the volume of an object totally immersed in a liquid. The situation prior to immersion
is shown in the Figure on the left, after immersion – on the right.
Variants of answer:
15 cm3.
20 cm3.
25 cm3.
30 cm3.
35 cm3.
1
3.
A 300 g solid with a volume of 300 ml is plunged into water. Choose the position of a solid after
immersion when equilibrium is established.
Variants of answer:
1
2
3
4
Answer depends on the mass of water.
4.
A 300 g solid with a volume of 0.4 l is plunged into water. Choose the position of the solid after
immersion when equilibrium is established.
Variants of answer:
1
2
3
4
Answer depends on the mass of water.
2
5.
A 300 g solid with a volume of 0.2 l is plunged into water. Choose the position of the solid after
immersion when equilibrium is established. .
6.
On which of the water-immersed steel balls does the maximum buoyant force act?
Variants of answer:
1
2
3
Force is the same for all balls.
Answer depends on the velocity of the second ball.
3
7.
A pot has a 2-liter capacity and is completely filled with water. A 0.6 kg object with a volume of
0.5 l is placed into the pot. How much water will leak out of the pot?
Variants of answer:
0.1 kg
0.5 kg
0.6 kg
1.4 kg
2.0 kg
8.
Two equal springs have a stiffness k (each) and are connected in parallel. Find the stiffness of
the composite spring. Enter the numerical answer:
Stiffness = k*
4
9.
Which bend of the U-type pipe contains the less dense liquid?
Variants of answer:
In the right.
In the left.
Densities are the same.
Such position of liquids is not possible.
Answer depends on the cross sectional area of the pipe.
10.
In what case do these books produce the maximum pressure on the table?
Variants of answer:
1
2
3
4
Pressure is the same in all cases.
5
11.
Suppose two U-type pipes containing two different liquids in each. Which pipe bend contains the
more dense liquid? (Indicate for cases A and B).
Variants of answer:
А – in the right. В – in the left.
А - in the right. В - in the right.
А - in the left. В - - in the right.
А - in the left. В – densities are the same.
А - in the right. В – densities are the same.
12.
Consider a solid cube immersed in a liquid. When will it sink? (ρ – The density of the cube’s
material, ρж – the density of the liquid)
Variants of answer:
ρ > ρl
ρ = ρl
ρ < ρl
in any case.
Answer does not depend on the density, but depends on the mass of the cube.
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13.
A 51 kg load is lifted at a constant speed by means of a weightless lever, the length of its shorter
arm L1 is 20 cm. Find the length of the other arm L2 (accurate to hundredths place), if the force
of 200 N, directed perpendicularly to the lever, acts on it. The value of the acceleration of gravity
is g = 9.8 m/s2.
Enter the numerical answer:
L2 =
m
14.
A homogeneous rod of constant cross-section is hanging horizontally on a loop of a rope. Will
the equilibrium be disturbed if we bend the rod to the right of the loop?
Variants of answer:
The right end of the rod will outweigh.
The left end of the rod will outweigh.
Equilibrium is not disturbed.
Answer depends on the bending position.
There is no correct answer among the answers given.
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15.
The hydrostatic pressure at the bottom of the water reservoir is 8000 Pa. Find the depth H of the
reservoir if the density of water is 1 g/cm3. The value of the acceleration of gravity take to be 10
m/s2.
Variants of answer:
H = 0.8 m
H = 8.0 m
H = 80 m
H = 800 m
H = 8000 m
16.
A 100 kg load is lifted at a constant speed by means of a horizontally placed lever, the length of
its shorter arm L1 is 20 cm. Find the length of the other arm L2, if the force of 200 N, directed
perpendicularly to the lever, acts on it.
Variants of answer:
L2 = 0.5 m
L2 = 1.0 m
L2 = 2.0 m
L2 = 5.0 m
Answer depends on the speed of lifting.
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17.
A small ball is placed at the bottom of the aquarium with water at a depth of 50 cm. Determine
the force produced by water and acting per one cm2 of the ball’s surface. The density of water is
1 g/cm3. The value of the acceleration of gravity take equal to 10 m/s2.
Variants of answer:
500 N
50 N
5N
0.5 N
0.05 N
18.
A car has a mass of 1600 kg. At which tire-to-road contact area will the pressure on the road be
400 kPa? The value of the acceleration gravity take to be 10 m/s2.
Variants of answer:
800 cm2
400 cm2
0.4 m2
0.1 m2
80 cm2
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19.
To keep a lever in equilibrium, the force F should be equal to:
Variants of answer:
3·m·g
m·g /3
3·m·g /4
4·m·g /3
m·g
20.
A weightless lever is in equilibrium. The ratio of the mass of a first load to the mass of a second
load is equal to:
Variants of answer:
4
3
1/3
1/4
3/4
10
21.
Mark all correct statements. In the absence of friction, an inclined plane….
Variants of the answer:
allows you to gain force advantage.
Allows you to gain advantage in work.
Allows getting an advantage in distance.
Gives neither advantage, nor loss.
Does not change the force with which it is necessary to act on the load during lifting.
22.
In order to lift the load uniformly by means of the depicted system of blocks, it is necessary to
pull the thread with the force of…
Variants of answer:
m·g
m·g/3
m·g/2
2·m·g
3·m·g
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23.
By how much will the level of tea in a glass increase, if a 21 g silver spoon is completely
plunged into it? The density of silver is ρ =10,5 g/cm³. The glass has a cylindrical shape and a
cross sectional area of 20 cm².
Variants of answer:
1 mm
2 mm
3 mm
4 mm
5 mm
24.
The weighing was carried out through the equal-arm balance, a cube of osmium (ρ =22.57
g/cm³) was counterbalanced by an iron cube (ρ=7.87 g/cm³). What is the length of an edge of a
cube of osmium if the length of an edge of a cube of iron is 20 mm?
Variants of answer:
7.0 mm
11.4 mm
12.3 mm
14.1 mm
16.2 mm
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25.
On what does the liquid pressure at the bottom of a vessel depend? Mark all correct statements.
Variants of answer:
on the bottom area of the vessel.
On the height of a liquid column.
On the acceleration of gravity.
On the shape of the vessel.
On the density of liquid.
26.
How does the pressure produced by a hammer on a nail differ from the pressure produced by the
nail on a board, if the nail-head area is S1=0.5 sm², the nail point area is S2=0.1 мм²? Forces of
the hammer on the nail are the same as the forces of the nail point on the board.
Variants of the answer:
The pressure produced by the hammer on the nail is 250000 times greater than the pressure
produced by the nail on the board.
The pressure produced by the hammer on the nail is 500 times greater than the pressure
produced by the nail on the board.
Pressures are equal.
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The pressure produced by the hammer on the nail is 500 times less than the pressure
produced by the nail on the board.
The pressure produced by the hammer on the nail is 250000 times less than the pressure
produced by the nail on the board.
27.
In a water filled complex-shaped vessel (see the Figure) a pressure in a point П increases by Δp
due to the action of a dashpot. Indicate the correct proportion for the pressure increment in points
1,2,3,4,5.
Variants of answer:
Δp5>Δp4>Δp3>Δp2>Δp1>Δp
Δp5<Δp4<Δp3<Δp2<Δp1<Δp
Δp2=Δp4<Δp<Δp1=Δp3=Δp5
Δp2=Δp4>Δp>Δp1=Δp3=Δp5
Δp5=Δp4=Δp3=Δp2=Δp1=Δp
28.
Why does an aluminum cube (ρ=2.7 г/см³) sink in the aquarium with water (ρ=1.0 g/sm³), while
an iron boat (ρ=7.9 g/sm³) of the same mass as the cube, floats? Since
(indicate all correct answers)
Variants of answer:
the density of iron differs from the density of water stronger than the density of aluminum
differs from the density of water.
The boat displaces a greater volume of water than does the cube.
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For the cube the buoyant force is less than the gravity force, for the boat – the buoyant
force is greater.
The volume of iron of the same mass is less than that of aluminum.
The form of the cube is more symmetrical.
29.
A 100 g potato floats in salt water (ρ=1.031 g/sm³) and sinks in fresh water (ρ=1.00 g/sm³). What
is the allowable volume V for a potato?
Variants of answer:
100 cm³<V<103 cm³
97 cm³<V<100 cm³
90 cm³<V<96 cm³
97 cm³<V<103 cm³
V = 100 cm³
30.
Why does the buoyant force act on an object in the air? Since…
Variants of answer:
the volume of gas decreases essentially when a high pressure is applied.
Gas cannot keep the form.
Gas tends to occupy all available volume.
The density of gas decreases with height.
The pressure of gas decreases with height.
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31.
A vacuum-sealed glass sphere is counterbalanced by means of sensitive weighing scales under
the bell jar of an air pump at atmospheric pressure. How will be the equilibrium of the scales
disturbed if we pump out the air under the bell jar? Why?
Indicate all correct answers.
Variants of answer:
If the volume of the sphere is less than that of a weighing pan and weights, the sphere goes
up.
If the volume of the sphere is greater than that of the weighing pan and weights, the sphere
goes down.
If the volume of the sphere is less than that of the weighing pan and weights, the sphere
goes down.
The buoyant force, which influenced on the equilibrium of the weighing scales, will
disappear.
In the absence of air, the sensibility of the weighing scales will increase.
32.
A piece of ice is floating in the vessel with water. When it melts, the level of water in the
vessel...
Variants of answer:
increases
decreases
remains the same
decreases if the piece of ice contains air bubbles, and increases if it does not contain air
bubbles.
Decreases if the piece of ice contains air bubbles, and remains the same if it does not
contain air bubbles.
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