List of top Physics Questions asked in CBSE Class XI

In Exercise 13.9, let us take the position of mass when the spring is unstreched as x = 0, and the direction from left to right as the positive direction of x-axis. Give x as a function of time t for the oscillating mass if at the moment we start the stopwatch (t = 0), the mass is 

(a) at the mean position, 

(b) at the maximum stretched position, and 

(c) at the maximum compressed position. 

In what way do these functions for SHM differ from each other, in frequency, in amplitude or the initial phase?

A spring having with a spring constant 1200 N m–1 is mounted on a horizontal table as shown in Fig. 13.19. A mass of 3 kg is attached to the free end of the spring. The mass is then pulled sideways to a distance of 2.0 cm and released. 

Determine (i) the frequency of oscillations, (ii) maximum acceleration of the mass, and (iii) the maximum speed of the mass

1. work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket. 
2. work done by gravitational force in the above case, 
3. work done by friction on a body sliding down an inclined plane, 
4. work done by an applied force on a body moving on a rough horizontal plane with uniform velocity, 
5. work done by the resistive force of air on a vibrating pendulum in bringing it to rest.

Which of the following relationships between the acceleration a and the displacement x of a particle involve simple harmonic motion? 

(a) a=0.7x 

(b) a= –200x ² 

(c) a=–10x 

(d) a=100x ³

A particle is in linear simple harmonic motion between two points, A and B, 10 cm apart. Take the direction from A to B as the positive direction and give the signs of velocity, acceleration and force on the particle when it is 

(a) at the end A, 

(b) at the end B, 

(c) at the mid-point of AB going towards A, 

(d) at 2 cm away from B going towards A, 

(e) at 3 cm away from A going towards B, and 

(f) at 4 cm away from B going towards A

Which of the following functions of time represent (a) simple harmonic, (b) periodic but not simple harmonic, and (c) non-periodic motion? Give period for each case of periodic motion (ω is any positive constant): 

(a) sin ωt – cos ωt 

(b) sin³ ωt 

(c) 3 cos (\(\frac{π}{4}\) – 2ωt) 

(d) cos ωt + cos 3ωt + cos 5ωt 

(e) exp (–ω ² t ² ) 

(f) 1+ωt+ω² t²

Figure 12.8 shows plot of \(\frac{PV}{T}\) versus P for 1.00×10–3 kg of oxygen gas at two different temperatures. 

(a) What does the dotted plot signify? 

(b) Which is true: T₁>T₂ or T₁<T_{2 ?} 

(c) What is the value of  \(\frac{PV}{T}\) where the curves meet on the y-axis? 

(d) If we obtained similar plots for \(1.00×10^–3\) kg of hydrogen, would we get the same value of \(\frac{PV}{T}\) at the point where the curves meet on the y-axis? If not, what mass of hydrogen yields the same value of  \(\frac{PV}{T}\) (for low pressure high temperature region of the plot) ? (Molecular mass of H₂ = 2.02 u, of O₂ = 32.0 u, R = 8.31 J mo1^–1 K^–1.)

1. magnitude of average velocity, and 
2. average speed of the man over the interval of time (i) 0 to 30 min, (ii) 0 to 50 min, (iii) 0 to 40 min ? [Note: You will appreciate from this exercise why it is better to define average speed as total path length divided by time, and not as magnitude of average velocity. You would not like to tell the tired man on his return home that his average speed was zero !].

1. magnitude of displacement (sometimes called distance) over an interval of time, and the total length of path covered by a particle over the same interval; 
2. magnitude of average velocity over an interval of time, and the average speed over the same interval. [Average speed of a particle over an interval of time is defined as the total path length divided by the time interval]. Show in both (a) and (b) that the second quantity is either greater than or equal to the first. When is the equality sign true ? [For simplicity, consider one-dimensional motion only].