Newton&39;s laws of motion PhO

Past paper of Physics Olympiad --- Newton's Laws of Motion 1.(03.1)

Ball A was dropped from the top of a tall building. At the same instant and from the same height ball B was thrown straight downward. Neglecting the effects of air friction, compare their accelerations while they were falling. A. Their accelerations are equal. B. Ball A has the greater acceleration. C. Ball B has the greater acceleration.

D. It is impossible to tell since their accelerations vary greatly. E. None of the above. 2.(03.2)

Two objects, A and B, accelerated from rest at the same uniform rate. Object B accelerated for a distance twice as long distance A. Compare to Object A, Object B was moving A. Twice as fast. B. 1.414 times as fast C. Three times as fast. D. Four times as fast. E. None of the above. 3.(03.4)

Which of the following statements is correct?

A. When you are not moving there is no force exerting on you. B. When there is no force exerting on you, you cannot move. C. When you are not moving there is no net force exerting on you. D. There must always be force acting on you when you move. E. None of the above. 4.(03.5)

A desk and a book are resting on the ground. Which of the following changes when the book is put on the desk?

A. The net force acting on the desk. B. The gravitational force acting on the desk.

C. The reaction force from the ground acting on the desk. D. The kinetic energy of the book. E. The kinetic energy of the desk.

5. (03.11)

Car A ran the red light and hit Car B which had the right of way at the intersection. Car A was more severely damaged than Car B, but fortunately no one was injured. You are to investigate the accident and decide which of the following statements is correct.

A. Driver of Car A was at fault because Car A collided with Car B before Car B collided with Car A.

B. Driver of Car A was at fault even though both cars collided at the same moment. C. Both drivers were at fault because both cars collided at the same moment.

D. Driver of Car B was at fault because Car B exerted more force on Car A, and as a result, car A was damaged more.

E. Driver of Car A was at fault because being the initiator Car A exerted more force on Car B. 6. (03.15)

In Newtonian mechanics the upper limit of speed any object could reach under constant action of a force F is ___. In Relativistic mechanics, however, the mass of an object is no longer a constant, but changes with the speed v of the object in the following way: m =Here c is the speed of light in vacuum,

and m0 is the mass when the object is at rest. Therefore, the maximum speed the object under constant action of force could reach is ___. A. , B. F/m, F/m0 C. F/ m0, F/m D. c, E. , c

7.(04.10)

We have seen on TV how the astronauts were trained in weightless condition in a large airplane. To achieve weightless condition the plane should ___. (A) Dive downwards at constant velocity

(B) Dive downwards at constant acceleration that is equal to g (C) Accelerate in horizontal direction (D) Move upwards at constant velocity

(E) Move upwards at constant acceleration that is equal to g

mo1v2

/c

2

8.(07.1)

It takes 240 s for the escalator to bring a boy, who is standing still, from the bottom to the top. If the boy walks on the moving escalator, it takes 60 s for him to reach the top. If the escalator is not operating, how long does it take for the boy to walk from the bottom to the top?

(A) 80 s (B) 140 s (C) 150 s (D) 60 s (E) 120 s

9.(07.2)

Ship A moves due north at 40 km/h, while ship B moves due west at 30 km/h. Find the relative speed between the two ships. (A) 10 km/h (B) 30/(C) 50 km/h (D) 40 km/h (E) 60 km/h

10.(08.1)

An object in constant acceleration motion with zero initial velocity covers 1 meter within

the 1st second. How many meters will it cover within the 4th(A) 7 (B) 1 11.(08.2)

Spaceship A moves at velocity 40(30 (xoyo ) km/s. Find the relative velocity in the unit of km/s between the two ships. (A) 10xo+ 10yo (D) 10xo+ 10zo

12.(08.4)

An object is in motion with constant acceleration. Which of the following statement is correct?

(A) The object must move in a straight line. (B) The distance traveled must be proportional to the square of the time. (C) The speed of the object must increase uniformly with time. (D) The velocity must be constant. (E) The total external force must do work to the object.

2 km/h (C) 9 (D) 3 (E) 16

xoyo) km/s, while spaceship B moves at (B) 10xo+ 70yo (C) 70(E) 10xo- 10yo

second?

xo+ 10yo

13.(08.15)

Two monkeys of the same weight are holding tightly the two ends of a rope with

negligible mass. The rope passes through a smooth pulley, as shown in the figure. The two monkeys are initially at rest. Now the left monkey starts to climbs up the rope at an average speed v relative to the pulley. Find its average speed relative to the right monkey.

(A) 0 (B) v upwards (C) 2v upwards (D) v downwards (E) 2v downwards

14.(09.1)

Spaceship-A moves at velocity 40(Spaceship-B moves at 30 (Spaceship-B in the fixed coordinate system in the unit of km/s. A. 10xo+10yo D. 70xo+10yo

15. (07.13)

A rocket is launched vertically upward from ground and moves at a constant

acceleration of 19.6 m/slaunch. To escape, the astronauts must eject at least 3 seconds before the rocket hits the ground. Neglect air resistance. How long will the astronauts have before ejection? A. 45.5 s B. 34.5 s

16. (09.14)

Object-A is dropped from a height upward from the ground. Right before they collide in mid-air, the speed of A is twice the speed of B. Determine the height where the collision occurs. A. 2h/3 B. h/3

Key: ABCCB EBACA

xo+yo) km/s relative to a fixed coordinate system. xo-yo) km/s as seen by Spaceship-A. Find the velocity of B. 10xo+70yo

C. 10E. 10xo-10yo

C. 6.5 s D. 41.5 s h. At the same instant object-B is thrown vertically h/4 D. h/2 E. BEADD A

xo+10zo

E. 13.5 s 2. By accident, the engine is suddenly shut off 10 seconds after

C. 3h/4

本文来源：https://www.bwwdw.com/article/dvlj.html