Английский язык. Ильичева Н.А - 19 стр.

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velocity, equals, zero (2), directly proportional, determine, divide, gravity,
inversely proportional, matter, multiply, acceleration

1. Determine the force necessary to give an object with a mass of 4 kg an
acceleration of 6 m/s2
We know that force a) ……. mass times b) …… (F = ma). To calculate the force
we must c) ……. 4 kg by 6 m/s2 and get 24 N.
2. A force of 2800 N is exerted on a rifle bullet with a mass of 0.014 kg. What
will be the bullet’s acceleration?
Acceleration is a) …… to the magnitude of force and b) …… ……. to the mass
of the object. To determine the bullet’s acceleration we must c) ……. 2.800 N
by 0.014 kg and get d) ……. m/s2.
3. What is the unbalanced force on a car moving with a constant velocity of 20
m/s (45 mi/h)
There is no change in a) ……. which means that the acceleration is b) ……. . It
also means that the force on a object is c) ……. .
4. What is the weight of a 6-kg package of nails?
Mass refers to the amount of a) …….. an object contains and weight is related to
the force of b) ……. . The acceleration due to gravity on the surface of the Earth
is equal to 9.8 m/s2. To c) …. we must multiply 6 kg by 9.8 m/s 2 to get 58.8 N.

13. Choose the right answer.
1. How does a rocket accelerate?
a) Rockets accelerate because the gases rushing out of the back of the engine
   push against the ground or the atmosphere.
b) A rocket exerts a strong force on the gases, expelling them; and the gases
   exert an equal and opposite force on the rocket, propelling it forward.
2. Can a person move a sled with a block of marble on it of a sled exerts an
   equal and opposite force backward?
a) No matter how hard he pulls, the backward reaction force always equals his
   forward force so the net (unbalanced) force must be zero. He’ll never be able
   to move this load.
b) The man can accelerate forward. There are two forces that affect his forward
   motion: (1) the force exerted on the person by the sled, pulling backward on
   him, and (2) the horizontal force exerted on him by the ground. When the
   ground pushes forward on the man harder than his sled pulls backward, the
   man accelerates forward.

14. Read the problem. Look at the sketches and answer the questions. Use
   the expressions: to be at rest, to act upward/downward, the net / the normal
   (perpendicular to the common surface of contact) force on the box is …., the
   force exerted by the table / by your friend is ….