Reinforcement Chapter 2

Reinforcement Chapter 2 Part A : Objective Questions1. When a coconut is falling to the ground, which of the following quantities is constant?

A.Velocity

B. Momentum

C. Acceleration

D. Kinetic energy2.In an inelastic collision, which of the following quantities remains constant before and after the collision?

A. Total acceleration

B. Total velocity

C. Total momentum

D. Total kinetic energy3.Calculate the weight of a stone with mass 60 g on the surface of the moon.

(The gravitational acceleration of the moon is 1/6 that of the Earth.)

A. 0.1 N

B. 0.2 N

C. 0.4 N

D. 0.6 N

E. 0.8 N

4.The momentum of a particle is dependent on

A. mass and acceleration

B. weight and force

C. mass and velocity 5. Which of the following diagrams shows a body moving at constant velocity?

A. 2 N 2N

B. 12 N 7 N

C. 12 N

14 N

D. 20 N

17 N

6.The graph below shows the motion of a trolley with mass 1.5 kg.

Velocity / ms-1

4

0 2 4 6 Time / s

Calculate the momentum of the trolley from t = 2s to t = 4s.

A. 1.5 kg m s-1

B. 3.0 kg m s-1 C. 4.0 kg m s-1 D. 6.0 kg m s-1 E. 7.5 kg m s-17.This figure shows an aircraft flying in the air.

8. m = 0.3 kg

5 m

What is the momentum of the stone just before it hits the ground?

A. 0.15 kg m s-1

B. 0.3 kg m s-1

C. 1.5 kg m s-1

D. 3.0 kg m s-1

E. 15.0 kg m s-1

9. A big ship will keep moving for some distance when its engine is turned off.

This situation happens because the ship has

A. great inertia

B. great acceleration

C. great momentum D. great kinetic energy10.An iron ball is dropped at a height of 10 m from the surface of the moon. Calculate the time needed for the iron ball to land. (Gravitational acceleration of the moon is 1/6 that of the Earth and g = 9.8 N kg-2)

A0.6 s

B1.4 s

C1.7 s

D3.5 s

E12.0 sPart B : Structure Questions1.

(i) Car A

(ii) Car B

Diagram 1.1

Diagram 1.1(i) and (ii) show two methods used by the mechanic to move a breakdown car. A constant force, F = 500 N is used to push and pull the car in method A and B.

(a) (i) Which method is easier to move the car?

(ii) State a reason for your answer in (a)(i).

(b) The frictional force acting between the car and track surface in both methods is 200 N. Calculate, the

(i) horizontal resultant force in method A.

(ii) horizontal resultant force in method B.

(iii) acceleration of the car in method B.

( c ) Suggest a method to move Car B so that the acceleration produced is equal to that of method A.

....

2.

ceiling

Tin water M N hand

P Q R

(i) Diagram 2.1

(ii)

a) Diagram 2.1(i) shows tin P that is empty and tin Q that is filled with water. A student find difficult to pushed tin Q. Write the inference about the observation.

b)Diagram 2.1(ii) shows a tin being released from the different positions M and N. The hand of a student at position R needs greater force to stop the motion of the tin falling from position M. Explain this observation.

c)Based on the observation (i) and (ii), state two factors that affect the magnitude of the momentum of the object.

d)If water flows out from a hole at the bottom of the tin Q, how would the inertia of Tin Q depends on time ?

3.

2 ms-1

P iron ball ( 2 kg )

S

T

3.0 m smooth surface

1.0 m

2.0 m

Q R

Diagram 3

Rough surfaceThe figure shows a iron ball that is rolled through PQRST. The rough surface of QR has frictional force of 4 N.

a) Calculate

(i) the kinetic energy of the iron ball at P.

(ii) the potential energy of the iron ball at P.

(iii) the total of energy of the iron ball at P.

b) (i)Calculate the total of energy of the iron ball when it reaches at Q ?

(ii) Calculate the work done against friction along QR.

c) Calculate the total kinetic energy of the iron ball at S.

d) Calculate the speed of the ball at position T.

Part C : Essay Questions

1.

(i) (ii)Diagram 1.1Diagram 1.1(i) shows the condition of a car moving at high velocity when it suddenly crashes into a wall.

Diagram 1.1(ii) shows a tennis ball hit with racquet by a player.

a)(i)What is the meaning of momentum?

(ii)Based on the observations of Diagram (i) and (ii), compare the characteristics of car when it crashes into the wall and the tennis ball when it is hit with a racquet. Hence, relate these characteristics to clarify a physics concept, and name this concept.

b)Explain why a tennis player uses a taut racquet when playing.

c) In launching a rocket, a few technical problems have to be overcome before the rocket can move upright to the sky. By using appropriate physics concepts, describe the design of a rocket and the launch techniques that can launch the rocket upright.

2.

BrandReaction time / sMass / kgEngine thrust force / NResistance force / N

A0.31.510.04.0

B0.51.812.52.4

C0.20.96.52.2

D0.62.516.06.5

In a radio-controlled car racing competition, 4 mini-cars branded A, B, C and D took part. The information of the 4 cars is given in the table above. Details of the above information are given as below;

Reaction time - Duration between the moment the radio-controlled is switched on and

the moment the car starts moving.

Resistance - Average value of opposing forces includes the friction between

wheels and track, and air resistance.

(a)What is the meaning of acceleration?

(b)Draw a graph of velocity against time that shows a car moving initially with constant acceleration, then moving with constant velocity and followed by constant deceleration until it stops.

(c) Explain the suitability of the properties in the above table in constructing a radio-controlled car racing purpose. Hence, determine which brand of car will win the 50-metre race.

(c) If Car B in the above table is moved up the plane at the angle of 30o to the horizon,

(i) Show that the car is able to move up the plane.

(ii) Determine the acceleration of the car.

Lift

Thrust Air friction

Weight

The aircraft above accelerates if

A. Lift ( Weight

B. Thrust ( Lift

C. Lift ( Air friction

D. Thrust ( Air friction

(

Properties

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