A person of mass 50 kg stands on a weighing scale on a lift. If the lift is descending with a downwards acceleration of 9 m/s² , what would be the reading of the weighing scale ?
When a lift descends with a downward acceleration 8, V the apparent weight of a body of mass m is given by w' = R = m (g - a)

2

(a)

Calculate the work done by a car against gravity is zero because force of gravity is vertical and motion of car is along a straight horizontal road.

2

(a)

Why does a solid sphere have smaller moment of inertia than a hollow cylinder of same mass and radius about an axis passing through their axis of symmetry?

2

(a)

A solid cylinder of mass 20 kg rotates about its axis with angular speed of 100 rad/s. The radius of cylinder is 0.25m. What is KE of rotation of cylinder?

2

(a)

A string of mass 2.5 kg is under a tension of 200N. The length of the stretched string is 20.0 m.If the transverse jerk is struck at one end of the string, the disturbance will reach the other end in.

2

(a)

At what temperature (in ⁰C) Will be speed of sound air be 3 times its value at 0⁰ C?

2

(a)

A person of mass 60 kg wants to lose 5 kg by going up and down a 10 m high stairs. Assume he burns twice as much fat while going up than coming down. If 1kg of fat is burnt on expending 7000 kcal calories, how many times must he go up and down to reduce his weight by 5 kg?

2

(a)

Consider a Carnot cycle operating between T₁=500K and T₂=300K producing 1kJ of mechanical work per cycle. Find the heat transferred to the engine by the reservoirs.

2

(a)

A gas mixture consists of molecule of types A, B and C with masses, m_A>m_B>m_C. Rank the three types of molecules in decreasing order of
(i) average KE
(ii)  rms speed

2

(a)

A steel wire has a length of 12 m and a mass of 2.10 kg. What will be the speed of a transverse wave on this wire when a tension of 2.06\(\times \)10⁴N is applied?

2

(a)

A pipe 20 cm long is closed at one end. Which harmonic mode of the pipe is resonantly excited by a source of 1237.5 Hz? (sound velocity in air = 330ms^-1)

2

(a)

At what temperature (in ⁰C) Will be speed of sound air be 3 times its value at 0⁰ C?

2

(a)

A sitar wire is replaced by another wire of same length and material but of three times the earlier radius. If the tension in the wire remains the same, then by what factor will the frequency change?

2

(a)

You have learnt that a travelling wave in one dimension is represented by a function y = f (x, t) where x and t must appear in the combination x – v t or x + v t, i.e. y = f (x ± v t). Is the converse true? Examine if the following functions for y can possibly represent a travelling wave :
(i) (x - vt) ²
(ii) log [(x + vt)/x₀]
(iii) 1/(x + vt)

2

(a)