PHYSICS ASSIGNMENT
CLASS – XI
CHAPTER - 4 (MOTION IN A PLANE)
Theory Based Questions:
Q1.A body projected horizontally moves with the same horizontal velocity although it is under the action of force of gravity. Why?
Q2.Define vectors. What is the essential condition for the addition of vectors? State and prove triangle law of vector addition.
Q3.What do you mean by dot product of two vectors? Mention important properties of scalar product of vectors. Given . Obtain the scalar product in rectangular components.
Q4.What do you mean by cross product of two vectors? Mention important properties of vector product of vectors. Given . Obtain the vector product in rectangular components.
Q5.What is a projectile? A projectile is fired with a velocity ‘u’ making an angle θ with the horizontal. Show that the trajectory is parabolic in nature. Also obtain expressions of its time of flight, maximum height and horizontal range.
Q6.State and prove parallelogram law of vector addition.
Q7.At what point in its trajectory does a projectile have its i) minimum speed, ii) maximum speed?
Q8.A skilled gunman always keeps his gun slightly tilted above the line of sight while shooting. Why?
Q9.State for each of the following physical quantities, if it is a scalar or a vector: volume, mass, speed, acceleration, density, number of moles, velocity, angular frequency, displacement, angular velocity.
Q10.Is it important in the long jump that how much height you take for jumping? What factors determine the span for a jump?
Q11.Define the terms i) angular displacement ii) angular velocity iii) time period iv) frequency, in connection with a circular motion.
Q12.Derive the relation between linear velocity and angular velocity.
Numerical Questions:
Q1.Two equal forces have their resultant equal to either. What is the inclination between them?
Q2.Two forces equal to P and 2P N act on a particle. If the first be doubled and second be increased by 20 N, the direction of the resultant is unaltered. Find the value of P.
Q3.Find unit vector parallel to the resultant of the vectors
.
Q4.A force is inclined at 30° to the horizontal. If its rectangular component in the horizontal direction is 50 N, find the magnitude of the force and its vertical component.
Q5.Find the value of λ so that the vectors are perpendicular to each other.
Q6.If unit vectors are inclined at angle θ, then prove that
.
Q7.Determine a unit vector perpendicular to both
.
Q8.Find the area of parallelogram formed by vectors
.
Q9.If R is the horizontal range for θ inclination and h is the maximum height reached by the projectile, show that the maximum range is given by .
Q10.Two bodies are thrown with the same initial velocity at angle α and (90°-α) with the horizontal. What will be the ratio of i) maximum heights attained by them and ii) their horizontal ranges?
Q11.A man can swim with a speed of 4km/hr in still water. How long does he take to cross a river 1km wide, if the river flows steadily at 3km/hr and he makes his strokes normal to the river current? How far from the river does he go when he reaches the other bank?
Q12.Rain is falling vertically with a speed of 30m/s. a woman rides a bicycle with a speed of 10m/s in the north to south direction. What is the relative velocity of rain with respect to the woman? What is the direction in which she should hold her umbrella to protect herself from the rain?
PHYSICS ASSIGNMENT
CLASS – XI
CHAPTER – 5 (LAWS OF MOTION)
Theory based questions
Q1.Define inertia. What are different types of inertia? Give one example of each type.
Q2.What is impulse? State and prove impulse-momentum theorem. Give two examples which make use of concept of impulse.
Q3.A body of mass m is placed on the floor of a lift. Find the apparent weight when the lift is:
a)moving upwards with acceleration ‘a’.
b)moving downwards with acceleration ‘a’.
c)moving with constant velocity.
d)at rest.
Q4.Discuss connected motion in detail. Also obtain necessary mathematical expressions for ‘T’ and ‘a’.
Q5.What do you understand by friction? Discuss the 3 types of friction. Also show them graphically.
Q6.Define angle of friction and angle of repose. Show that these two angles are equal to each other.
Q7.Find an expression for the work done against friction when a body is made to slide i) up an inclined plane, ii) down an inclined plane.
Q8.How does friction help us in walking?
Q9.State Newton’s second law of motion.
Q10.While firing, the gun should be held tightly to the shoulder of the shooter. Why?
Q11.What is meant by banking of roads? What is the need for banking a road? Obtain an expression for the maximum speed with which a vehicle can safely negotiate a curved road banked at an angle ‘θ’.
Q12.When a horse pulls a cart, according to Netwon’s third law, the cart also pulls the horse with an equal and opposite force. What causes the motion of the horse, the cart and the system as a whole? Explain with a diagram.
Numerical Questions:
Q1.A force of 49N is just sufficient to pull a block of wood weighing 10kg on a rough horizontal surface. Calculate the coefficient of friction and angle of friction.
Q2.A ball moving with a momentum of 5kgm/s strikes against a wall at an angle of 45° and is reflected at the same angle. Calculate the change in momentum.
Q3.A body of 5 kg mass is supported by a cord or string. Calculate the tension in the cord if the body is i) at rest, ii) moving with uniform velocity, iii) accelerating upwards at 3m/s2, iv) accelerating downwards at 2m/s2. (Take g=10m/s2)
Q4.A rubber ball whose mass is 10g falls from a height of 40m and rebounds to a height of 10m. Find the impulse and the average force between the rubber ball and the floor if the time during which they are in contact is 0.1s.
Q5.An elevator and its load weigh a total of 800kg. Find the tension ‘T’ in the supporting cable when the elevator, originally moving downwards at 20m/s is brought to rest with constant retardation in a distance of 50m.
Q6.A car of mass 1000kg travelling at 32m/s dashes into the rear of a truck of mass 8000kg moving in the same direction with a velocity of 4m/s. After the collision the car bounces with a velocity of 8m/s. What is the velocity of the truck after the impact?
Q7.When an automobile moving with the speed of 36km/hr reaches an upward inclined road of incline 30°, its engine is switched off. If the coefficient of friction involved is 0.1, how much distance will the automobile move before coming to rest? (Take g=10m/s2)
Q8.A body of weight 200N is suspended with the help of strings as shown in figure. Find the tensions T1 and T2.
Q9.While launching a rocket of mass 2x104kg a force of 5x105N is applied for 20s. Calculate the velocity attained by the rocket at the end of 20s.
Q10.A body M1 of mass 10kg is placed at the centre of a smooth horizontal table and is held stationary using a nail. It is connected to a string which passes over a friction less pulley fixed at the end of the table. The string carries at the other end a body M2 of mass 5kg. What acceleration will be produced in the bodies when the nail is removed? What will be the tension in the string during the motion of the bodies and when the bodies come to rest? (Take g=9.8m/s2)
Q11.Calculate the angel through which a cyclist bends from the vertical when he crosses a circular path of 34.3m in circumference in s.(Take g=9.8m/s2).
Q12.A circular race track of radius 300m is banked at an angle of 15°. If the coefficient of friction between the wheels of a race car and the road is 0.2, what is the i) optimum speed of the race car to avoid wear and tear on its tyres, and ii) maximum permissible speed to avoid slipping.
Q13.An airplane travelling at a speed of 500km/hr tilts at an angle of 30° as it makes a turn. What is the radius of the curve?
PHYSICS ASSIGNMENT
CLASS – XI
CHAPTER – 6 (WORK ENERGY AND POWER)
Theory based questions
Q1.State and prove work energy theorem.
Q2.Show that the total mechanical energy of a body falling freely under gravity is conserved. Show it graphically.
Q3.Discuss elastic collision of two bodies in one dimension. Calculate the velocities of the bodies after the collision. Also discuss all the special cases.
Q4.What is meant by positive work, negative work and zero work? Give one example of each type.
Q5.What are conservative and non-conservative forces?
Q6.Define the term power. Is it a scalar or vector quantity? Give its dimension and unit.
Q7.Does the work done in raising a suit case on to a platform depend up on how fast it is raised up?
Q8.When a constant force is applied to a body moving with constant acceleration, is the power of the force constant? If not, how would force have to vary with speed for power to be constant?
Q9.State if each of the following statements is true or false. Give reasons for your answer.
a)In an elastic collision of two bodies, the momentum and energy of each body is conserved.
b)Total energy of a system is always conserved, no matter what internal and external forces on the body are present.
c)Work done in the motion of a body over a closed loop is zero for every force in nature.
d)In an inelastic collision, the final kinetic energy is always less than the initial kinetic energy of the system.
Q10.What physical quantity does the area under the force displacement curve represent?
Numerical Questions:
Q1.A force N is applied on a body which is sliding over a floor. If the body is displaced through (m), how much work is done by the force?
Q2.A shot travelling at the rate of 100m/s is just able to pierce a plank 4cm thick. What velocity is required to just pierce a plank 9cm thick?
Q3.If the linear momentum of a body increases by 20%, what will be the % increase in the kinetic energy of the body?
Q4.A string of a pendulum is 2m long. The bob is pulled sideways so that the string becomes horizontal and then the bob is released. What is the speed with which the bob arrives at the lowest point? Assume that 10% of the initial energy is dissipated against air resistance. (Take g=10m/s2)
Q5.The kinetic energy of a body decreases by 19%. What is the percentage decrease in its linear momentum?
Q6.The length of the steel wire increases by 0.5cm when it is loaded with a weight of 5kg. Calculate i) force constant of the wire, ii) work done in stretching the wire.
Q7.A man weighing 60kg climbs up a stair case carrying a load of 20kg on his head. The stair case has 20 steps each of height 0.2m. If he takes 10s to climb, find his power.
Q8.A 10kg ball and 20kg ball approach other with velocities 20m/s and 10m/s respectively. What are their velocities after collision if the collision is perfectly elastic?
Q9.A railway carriage of mass 9000kg moving with a speed of 36km/hr collides with a stationary carriage of the same mass. After the collision the carriages get coupled and move together. What is their common speed after collision? What type of collision is this?
Q10.A girl of mass 40kg sits in a swing formed by a rope of 6m length. A person pulls the swing to a side so that the rope makes an angle of 60° with the vertical. What is the gain in the potential energy of the girl?