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Physics Grade 11 Unit 4: DYNAMICS

76 national exam questions have come from this unit. It runs 80 pages; one careful study pass takes about 9.5 hours, and its difficulty is harder among Physics units. Each section below lists the questions set from it, with the year, and opens the page that teaches it.

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4.1 The Concept of Force and Newton’s Laws of motion · read p. 96

2016 E.C., Q15 – A body is observed to be moving with constant velocity in a straight line. One can surely conclude that for this body,
2015 E.C., Q21 – Suppose you are standing on a horizontal floor, in a room, with one of your feet and leaning the wall of the room with the other foot. The number of action reaction pair of forces you experience is
2010 E.C., Q6 – Both boys are drawn about the same size; no forces or numerical values are marked.]
2007 E.C., Q18 – Which one of the following statements is not correct about a particle that is in equilibrium?
2005 E.C., Q3 – What is the direction with which a fish must push the water with its fins in order to propel eastward?

4.2 Frictional Force · read p. 112

2018 E.C., Q13 – Static friction force is different from kinetic friction force in that, it:
2018 E.C., Q35 – A block of mass 20.0 kg is placed on a horizontal surface. If the coefficient of kinetic friction between the block and the surface is 0.25, what force must be applied on the block to accelerate it uniformly with 3.0 m/s
2017 E.C., Q20 – When an object tends to slide over the surface of another object, tiny bumps at the surface of the two objects knocking and locking together. This causes
2017 E.C., Q23 – A 2 kg object accelerates with to the right on a horizontal frictionless surface under the action of two F 1 F 2 F 1 horizontal forces, and as shown in the figure below. What should be the magnitude of ? Question Diagram
2016 E.C., Q26 – A student of mass 40 kg is in a lift moving upward with an acceleration of 2.5 m/s 2 . What is the apparent weight of the student?
2015 E.C., Q47 – A man pushes a 25.0 kg object by 250 N force along an inclined plane inclined at an angle of 37° to the horizontal. If the object moves with constant speed, the friction force exerts on the block is
2014 E.C., Q27 – The apparent weight of a 60 kg student standing inside a lift is
2014 E.C., Q26 – Which one of the following statements describes the difference between different types of friction?
2013 E.C., Q42 – Which one of the following statements is NOT correct about the concept and units of coefficient of friction?
2013 E.C., Q12 – A mass-spring system set to oscillate in a simple harmonic motion over friction less horizontal surface. The amplitude of this oscillation is 20 cm. A second mass-spring system with the same spring constant is set to osc
2012 E.C., Q23 – A force labeled pulls block horizontally to the right with an arrow.] a = 2/3 m/s2 T = 1 2/3 N T = 2 2N a = 3/2 m/s2 T = 1 3/2 N T = 2 9/2 N
2011 E.C., Q9 – A 5 kg mass pushed upward along an inclined plane of inclination with constant force F. If the acceleration 1.0 m/s2 of the block for this motion is and the plane is assumed to be friction less, what is the magnitude of
2011 E.C., Q14 – In which of the following case is no work done by a dissipative force?
2010 E.C., Q12 – Three objects sit near the top edge of the ramp, each named by a leader line drawn from a label on the left: "sphere" points to a ball at the top, "Solid cylinder" points to a short cylinder just below it, and "ring" poi
2008 E.C., Q1 – A man is standing on a spring scale in an elevator. When the elevator is at rest, the scale reads 560N. When the elevator stars to move, the scale reads 600N. The elevator has
2007 E.C., Q16 – From the pulley a vertical string labelled hangs straight down and is attached to the top of a second, unshaded rectangular block labelled 3 kg.] 2 0.40 kgm2 0.80 kgm2
2007 E.C., Q9 – A stray label "C(1,4)" is printed immediately after the angle; it is a scanning artifact carried over from a neighbouring figure and belongs to no part of this problem.] 10 m/s2 5.2 m/s2
2006 E.C., Q47 – A 10.0m uniform ladder weighing 200N rests against a frictionless wall. The ladder makes angles with the horizontal, if the ladder is just on the verge of slipping when a 600.0N firefighter is 6.00m along the ladder from
2006 E.C., Q24 – No numeric values appear on the drawing itself.]
2005 E.C., Q22 – A $2\text{kg}$ object experiences two concurrent forces of $100\text{N}$ at $30^\circ$ above the positive x-axis and $80\text{N}$ at $60^\circ$ above the negative x-axis. What is the magnitude of acceleration of the obje

4.3 The First Condition of Equilibrium · read p. 126

Not asked in a national paper yet.

4.4 Work, Energy and Power · read p. 128

2018 E.C., Q33 – In an automobile that contains engine and fuel, chemical energy of the fuel is partially converted to kinetic energy of the automobile and partially to thermal energy. In this process, the:
2018 E.C., Q15 – A forklift truck applied a force of F = 30 N, East on an object and dragged it through a distance of 200 m along a horizontal frictionless surface in a time of 5 minutes. The average power output of the truck is:
2017 E.C., Q57 – A spring stores 120 J of elastic potential energy when it is stretched by 0.5 m. What is the potential energy stored by the spring when it is stretched by 1.5 m?
2017 E.C., Q21 – Suppose a ball is thrown vertically upward and after reaching a maximum height, it returns back to its initial position. Which of the following statement is correct about energy changes and work done on the ball?
2016 E.C., Q46 – If a ball is thrown vertically upward with an initial velocity of v 0 and reaches a maximum height h after time t, then during the time interval
2014 E.C., Q9 – According to the work- energy theorem,
2012 E.C., Q27 – Distinguish between conservative and non-conservative forces.
2012 E.C., Q26 – Identify the correct statement about energy, work, and force.
2012 E.C., Q28 – A crane raises $75.0\,\mathrm{Kg}$ of bricks from the ground to a height of $45.0\,\mathrm{m}$ in $52.0\,\mathrm{s}$ a constant speed. The average power of the crane is?
2011 E.C., Q12 – Which of the following is equal to the amount of work required to stop a moving object ?
2009 E.C., Q6 – A spring with a spring constant of 300N/m is stretched 20cm in 2 seconds. What is the power applied to stretch the spring?
2009 E.C., Q7 – A 50KW machine is used to lift heavy objects to the top of a building under construction. If this machine is replace with a new machine of 100KW power, then which of the following statements is not true about the new mac
2009 E.C., Q8 – Which of the following is correct about a work done for dissipative force?
2008 E.C., Q16 – Which statement is correct about conservative and dissipative force?
2007 E.C., Q14 – A block of mass 10kg is pulled up a rough inclined plane with a force of 100N parallel to the inclined plane. The inclined plane makes an angle of 370 with the horizontal. At the instant when the force is applied the blo
2007 E.C., Q13 – Which one of the following statements is true about a spring mass system oscillation on a horizontal frictionless surface?
2007 E.C., Q12 – A car of mass 1500 kg is travelling at a uniform velocity of 30m/s due east. The driver applies the brakes to slow down the car to a velocity of 10m/s due east. What is the work done in slowing down the car?
2006 E.C., Q10 – Two men, A and B, are loading identical boxes onto a truck. A lifts his box staring up from the ground to the bed of the truck, whereas B slides his box up a rough ramp to the truck, which statement is correct about the
2005 E.C., Q44 – Gas at a pressure P is contained in a vessel. If the masses of all the molecules are doubled and their speeds are half, then what will be the resulting pressure?
2005 E.C., Q16 – A woman driving a 2000 kg car along a level road at 30m/s takes her foot off the gas to see how far her car will roll before it slows to a stop. She discovers that it takes 150m.What is the average force of friction acti

4.5 Conservation of mechanical energy · read p. 144

2017 E.C., Q22 – The mechanical energy of an oscillating object at any point through its path is equal to
2013 E.C., Q46 – Suppose that you are given a mass attached to a spring and oscillates up and down. This mass-spring system has maximum gravitational potential energy (GPE), elastic potential energy (EPE) and kinetic energy (KE) at:
2006 E.C., Q18 – A hoop of mass $M$ and radius $R$ is at rest at the top of an incline plane of height $h$. the hoop rolls down the plane without slipping. When the hoop reaches bottom, its angular momentum about its center of mass is:
2005 E.C., Q30 – A uniform ball of radius r and mass m starts from rest and rolls down a frictionless inline of height h. when the ball reaches the ground, how fast is it going?

4.6 Impulse and Linear Momentum · read p. 148

2018 E.C., Q31 – During collision between two objects, the impulse imparted on each object is equal to the:
2018 E.C., Q36 – A 0.3 kg ball moving with a velocity of 0.9 m/s along the positive x-axis collides with a 0.2 kg ball moving with a velocity of 1.2 m/s along the negative x-axis. What is the velocity of the center of mass of the two bal
2017 E.C., Q1 – Block A of mass m₁ = 8.0 kg is travelling initially at u₁ = 6.0 m/s in the positive x-direction. It collides with block B of mass m₂ = 12.0 kg, which is moving in the same direction with velocity u₂ = 3.0 m/s. If immedia
2017 E.C., Q60 – A system of four masses , , , and are located in the xy-plane at the coordinates of , , , and , respectively. What is the coordinate of the center of mass of the system?
2017 E.C., Q24 – A tennis ball of mass 0.10 kg traveling horizontally at 40.0 m/s is struck back by a racket. If the ball returns back with a speed of 30.0 m/s in the opposite direction, what is the magnitude of the impulse delivered to
2016 E.C., Q12 – Which one of the following is correct about the assumptions made in the kinetic theory of ideal gases?
2016 E.C., Q17 – A constant torque of 80 Nm is applied to the rim of a flywheel for 2 s. If the flywheel initially has angular momentum of 40 kgm 2 /s, what will be its final angular momentum?
2015 E.C., Q48 – The following three collisions occur in different systems. I. A billiard ball A collides with an identical ball B and comes to rest after collision, while ball B moves with the same velocity as ball A was moving before.
2015 E.C., Q24 – A car of mass 1.50 × 10³ kg collides with a wall and rebounds. The initial and final velocities of the car are $v_1 = -15.0$ m/s and $v_2 = 2.60$ m/s respectively. If the collision lasts for 0.15 s, what is the magnitude
2015 E.C., Q9 – Consider a system of two point masses M1 and M2 with M1 = 0.5 M2. The two masses are located on the x-y plane as shown in the figure below. Which one of the following alternatives indicates the position of center of mass
2014 E.C., Q15 – According to the Heisenberg's uncertainty principle,T
2013 E.C., Q45 – Consider two collisions that occurred between two trollies having the same mass, moving with the same speed, and in opposite directions. Collision 1: after collision the two trollies bounce back with the same speed. Coll
2013 E.C., Q44 – Which one of the following statements is correct about the impulse on an object?
2012 E.C., Q12 – According to the kinetic theory of gases, the
2012 E.C., Q31 – Identify the correct statement about torque and angular momentum.
2011 E.C., Q11 – The rate of change of momentum of the raindrop can be given by u In this expression what does represent?
2010 E.C., Q15 – For a constant force F, if the impulse imparted to the system is large, then what can you conclude about the collision?
2008 E.C., Q2 – What is the necessary and sufficient condition for conservation of linear momentum?
2008 E.C., Q15 – A net external non zero force acts on a particle that is moving along a straight line which one of the following statements is correct?
2008 E.C., Q12 – Below the right block a horizontal arrow VA = VB 20 s m points to the right, and to its right is written to the right.]
2007 E.C., Q10 – A hard ball moving on a horizontal frictionless surface with a speed of 5m/s in the positive x direction strikes a stationary hard ball of the same mass. After the collision, the first ball moves with a speed of 4m/s alo
2006 E.C., Q32 – Two particles with masses 2m and 3m are moving toward each other along the x axis with the same initial speed v. Particle 2m is traveling to the left, and particle 3m is traveling to the right. They undergo an elation gl
2005 E.C., Q47 – A rocket moving in free space has a speed of $3\times10^3\,\text{m/s}$ relative to the earth. Its engines are turned on and fuel is ejected in a direction opposite the rocket's motion at a speed of $5\times10^3\,\text{m/
2005 E.C., Q21 – A $1.5\text{kg}$ particle moves in the xy-plane with velocity $\vec{v}=(4.2\vec{i}-3.6\vec{j})$ what is its angular momentum when the position vector is $\vec{r}=(1.5\vec{i}+2.2\vec{j})\text{m}?$
2005 E.C., Q33 – If two particles have equal momenta, then which one of the following statements is TRUE about their kinetic energies?