English for Phisic

Unit 2
PRACTICE &
HOMEWORK EXERCISES
GROUP 4
CONTENT
PRACTICE AND HOMEWORK EXERCISES
UNDERSTADING THE READING
WORKING WITH THE VOCABULARY
FURTHER WORD
UNDERSTADING THE READING
Answer the following questions by referring to the reading passage.
1. What is a motion?
Motion is typically and carefully described in terms of distance, displacement, time, velocity, acceleration and speed.
2. What do the Newton’s laws of motion state?
 If an object isn’t affected by any force or is affected whose resultant force is zero, a rest object will continue to be stationary; a moving object will continue to move linearly and uniformly.
UNDERSTADING THE READING
Answer the following questions by referring to the reading passage.
3. What is gravitation?
 Gravitation, the attractive force between all objects that tend to pull them toward one another.
4. Who did the Copernicus system further develop?
 Johannes Kepler further develop Copernicus system.

UNDERSTADING THE READING
Answer the following questions by referring to the reading passage.
5. How do the Kepler’s laws state?
 1. The orbit of a planet is an ellipse with the Sun at one of the two foci.
2. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
3. The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
UNDERSTADING THE READING
Answer the following questions by referring to the reading passage.
6. What did Newton use to arrive at his law of universal gravitation?
Newton used Kepler’s law to arrive at his law of universal gravitation.
7. What do Newton’s third law of motion require?
Newton’s third law of motion requires that the force a planet exerts on the sun equal in magnitude to the force of the sun exerts on the same planet.
UNDERSTADING THE READING
Decide whether each of the following statements is true (T), false (F) or with no information to clarify (N) Then make the necessary changes so that the false statements become true.
UNDERSTADING THE READING
Decide whether each of the following statements is true (T), false (F) or with no information to clarify (N) Then make the necessary changes so that the false statements become true.
UNDERSTADING THE READING
Decide whether each of the following statements is true (T), false (F) or with no information to clarify (N) Then make the necessary changes so that the false statements become true.
UNDERSTADING THE READING
Decide whether each of the following statements is true (T), false (F) or with no information to clarify (N) Then make the necessary changes so that the false statements become true.
UNDERSTADING THE READING
Word form
Emit  re-emit
Arrange  re-arrange
Construct  re-construct
Radiate  re-radiate
Solve  re-solve
Orient  re-orient
Please add the prefix re- to each word in the right column. Then choose the correct word to complete each sentence.
UNDERSTADING THE READING
Word form
Please add the prefix re- to each word in the right column. Then choose the correct word to complete each sentence.
re-emit re-arrange re-construct e-radiate re-solve re-orient
a. The atoms or molecules of the nonconductor …….….. themselves so that their constituent electrons are as far as possible from the negatively charged body.
b. To… …….….. …..these conflicts Einstein developed an entirely new approach to the concept of gravity, based on the principle of equivalence.
c. These gases then … …….….. …..infrared radiation, some of which strikes and is absorbed by the earth.

UNDERSTADING THE READING
Word form
Please add the prefix re- to each word in the right column. Then choose the correct word to complete each sentence.
re-arrange re-construct re-radiate
d. The No.1 and No.2 reactors, in fact, were returned to service in November 1986 and the slightly damaged No.3 unit was … …….….. ….. in December 1987.
e. In this process, electrons in the molecules are set in vibration by the electric fields of the light waves, and the vibrating electrons then … …….….. …..
f. These signals are … …….….. ….. when the brain processes them into an image that is right side up.
WORKING WITH THE VOCABULARY
Complete each of the following statements with words/ phrases from the reading passage
Radius gravitation inversely spin speed inertia
Displacement stationary conservation velocity mass revolutio
1. Motion is typically and carefully described in terms of distance … …….….. ….. time, velocity, acceleration and speed.
2. If an object isn’t affected by any force or is affected whose resultant force is zero, a rest object will continue to … …….…. a moving object will continue to move linearly and uniformly.

WORKING WITH THE VOCABULARY
Complete each of the following statements with words/ phrases from the reading passage
Radius gravitation inversely spin speed inertia
conservation velocity mass revolution
3. Acceleration (the change of the momentum, or velocity) of an object has the same direction with the force affecting the object, the magnitude of the acceleration is directly proportional to the magnitude of force and … …….…. proportional to the mass of the object.
4. Newton`s third law also requires the … …….…. of momentum, or the product of mass and velocity.
WORKING WITH THE VOCABULARY
Complete each of the following statements with words/ phrases from the reading passage
radius gravitation spin speed inertia
velocity mass revolution
5. Without gravitation, the … …….…. of the earth would send them floating into space.

6. Each planet moves so that ar … …….…. vector from the sun to it swepts out equal areas in equal times.

WORKING WITH THE VOCABULARY
Complete each of the following statements with words/ phrases from the reading passage
gravitation speed inertia
velocity mass revolution
7. Kepler’s third law indicated that how long it takes to make one complete … …….…. (in relation to the size of the orbit).

8. Newton used Kepler’s third law to acheive at his law of universal … …….….
WORKING WITH THE VOCABULARY
Choose the best word or phrase for each sentence
velocity
gravity
orbit
inertia
gravitational
internal
balanced
magnitude
additional
1. Kepler’s laws states that all planets move in elliptical …………….. with the sun at one focus.
2………………… is the property of all objects, which tends to conserve the velocity in both the direction and magnitude.
3.Mass has the………………… property: when many objects are put together into a body system, the mass of that system is total of mass of those object.
orbit
inertia
additional
WORKING WITH THE VOCABULARY
Choose the best word or phrase for each sentence
velocity
gravity
gravitational
internal
balanced
magnitude
4. Action and reaction forces are not ……………….. because they act on two different objects.

5. When two objects interact each other, they form a system. The interactive force between two objects is called …………… force.

6. The ……………….. force between any two particles is directly proportional to the product of their two masses and inversely to the distance square between them.
balanced
gravitational
WORKING WITH THE VOCABULARY
Choose the best word or phrase for each sentence
velocity
gravity
magnitude
 
velocity
magnitude
FURTHER WORD
Multiple choice
1. Which sentence is right?
a. The acceleration of a uniform accelerated linear motion is always greater than the one of a uniform decelerated linear motion.
b. If a uniform accelerated linear motion has great acceleration, it has great velocity.
c. A uniform accelerated linear motion has the acceleration increasing or decreasing steadily over time.
d. The acceleration in a uniform accelerated linear motion has constant direction, dimension and magnitude.
FURTHER WORD
Multiple choice
2. According to Keller third law, the time needed for a planet to go around the sun
a. depends on its mass
b. depends on the average radius of its orbit
c. depends on its speed of rotation
d. is the same for all the planet
FURTHER WORD
Multiple choice
3. An object is moving with the velocity of 3m/s. If suddenly forces acting on it disappear
a. the object stops immediately
b. the object changes the direction of motion
c. the object slows down and stops
d. the object continues to move in the former direction with the velocity 3m/s
FURTHER WORD
Multiple choice
4. A 0,5kg ball is lying at rest on the ground. A football player is shooting the ball with a force of 250N. The time that the foot acts on the ball is 0,02s. The ball is flying with the speed of:
a. 0,01 m/s b. 0,1 m/s
c. 2,5 m/s d. 10 m/s
FURTHER WORD
Multiple choice
5. An 8 kg object slides down a smooth inclined plane with the acceleration of 2 m/s2. Compare the magnitude of the force causing this acceleration with the weight of the object. Take g = 10 m/s2.
a. 1,6 N, smaller b. 16 N, smaller
c. 160 N, greater d. 4N, greater
FURTHER WORD
Multiple choice
6. An astronaut is “weightless” in a spacecraft
a. as it takes off from the earth
b. in certain orbits only
c. in all orbits
d. only when the escape speed exceeds
FURTHER WORD
Multiple choice
7. The gravitational acceleration of an object
a. has the same value everywhere in space
b. has the same value everywhere on the earth’s surface
c. varies somewhat over the earth’s surface
d. is greater on the moon because of its smaller diameter
FURTHER WORD
Multiple choice
8. An 1kg object on the ground has the weight of 10N. When it is moved to a point 2R from the center of the Earth (R is the radius of the Earth). What is its weight?
a. 1 N b. 2,5 N
c. 5 N d. 10 N
FURTHER WORD
Multiple choice
9. Action and reaction forces are:
a. two balanced forces
b. two contact forces
c. two opposite–acting forces
d. two elastic forces
FURTHER WORD
Multiple choice
10. A woman whose mass is 60 kg on the earth’s surface is in a spacecraft at a height of twice the earth’s radius (that is, 2 earth radii) above the earth’s surface. Her mass there is
a. 6.7 kg b. 15 kg
c. 20 kg d. 60 kg
Translate into English
FURTHER WORD
1. Trọng lực của một vật là lực hấp dẫn giữa Trái Đất và vật đó.
 Gravity of an object is gravitation between the Earth and this object.
2. Trọng tâm của vật là điểm đặt của trọng lực của vật.
 The focus of the object is setpoint of object’s gravity.
3. Khối lượng là đại lượng vô hướng, dương, không đổi đối với mỗi vật.
Mass is scalar quantity, positive, constant with the objects.
Translate into English
FURTHER WORD
4. Gia tốc là đại lượng đặc trưng cho sự thay đổi vận tốc của một vật. Nó được đo bằng sự nhanh hay chậm của chuyển động của một vật thể thay đổi theo thời gian.
 Acceleration is specify quantity for changing velocity of an object. It is measured by the increasing or decreasing of object’s motion changing overtime.
5. Trong tương tác giữa hai vật, một lực gọi là lực tác dụng còn lực kia gọi là phản lực.
 In the interaction between two objects, the one is called the action force another one is reaction force.
2.3.3 Speak out loudly and state the meaning of the following fomula
sqequal V zero (or V nought) t plus one halt at squared
squared minus V zero squared equal 2as
F equal Gmamb over r squared.
V Vector equal the derivative of r vector by t.
K equal T squared over r cubed.
a vector equal minus of vectors V and V zero over t minus t zero equal Delta v vector over delta t.
Exercises
FURTHER WORD
1. If the orbit of Mars is 1.52 times greater than the orbit of Earth, determine how much it takes Mars to complete one orbit?
 
Exercises
FURTHER WORD
2. The moon is 3.84x108m from the Earth and circles the earth once every 27.3 days. Compare the moon’s centripetal acceleration with the acceleration it would experience on the basis of Newton’s law gravitation.
 
Exercises
FURTHER WORD
3. Calculating the weight of an 75kg astronaut when he is:
a. on the Earth (take g = 9,8 m/s2)
b. on the Moon (take gm = 1,7 m/s2)
c. on the Venus (take gv = 8,7 m/s2)

On the Earth: P = mg = 75 x 9,8 = 735 N
On the Moon: Pm = mgm = 75 x 1,7 = 127,5 N
On the Venus: Pv= mgv = 75 x 8,7 = 652,5 N
The End