The Flosberry's Flop

Q.

A metal bar 70 cm long and 4kg in mass is supported on two knife edges placed 10cm from each end. A 6 kg weight is suspended at 30cm from one end. Find the reaction at knife edges. (assume the bar to be uniform cross section and homogeneous). Take g=9.8m/s2

Q. What are point masses

Q. Two small charged ball are suspended with two insulating string of length l from same point. assume mass of ball is m and the length of string is very large. If the whole system is emerged in kerosene having dielectric cons†an t two then, what should be the angle theta with vertical in equilibrium. ( relative density of kerosene is rho)

Q. A body of mass M kg is suspended by a weightless string.calculate the horizontol force that is required to displace it untill the string makes an angle of 45 degree with the initial vertical direction

Q.

You may have seen in a circus a motorcyclist driving in vertical loops inside a ‘death-well’ (a hollow spherical chamber with holes, so the spectators can watch from outside). Explain clearly why the motorcyclist does not drop down when he is at the uppermost point, with no support from below. What is the minimum speed required at the uppermost position to perform a vertical loop if the radius of the chamber is 25 m?

Q.

In which of the following cases center of mass is not inside the body

1. Semicircular disc with varying density

2. a Non uniform rod

3. hollow metallic sphere

4. a Flosbury flop

Q. Centre of mass of a system is a unique point which is very helpful in solving the problems related to the motions of rigid bodies. In columns I and II, some statements regarding centre of mass are given. Match the columns

Q.

The main reason that a Flosbury flop was so efficient was

1. center of mass was kept above the pole using less force

2. center of mass was below the pole

3. it uses aerodynamics to leviate the body

4. it made you superman

Q.

In which of the following cases center of mass is not inside the body

1. Semicircular disc with varying density

2. hollow metallic sphere

3. a Non uniform rod

4. a Flosbury flop

Q. A metal sphere of radius 1 mm and mass 50 mg falls vertically in glycerine. Find (a) the viscous force exerted by the glycerine on the sphere when the speed of the sphere is 1 cm s⁻¹, (b) the hydrostatic force exerted by the glycerine on the sphere and (c) the terminal velocity with which the sphere will move down without acceleration. Density of glycerine = 1260 kg m⁻³ and its coefficient of viscosity at room temperature = 8.0 poise.

Q.

The main reason that a Flosbury flop was so efficient was

1. center of mass was kept above the pole using less force

2. it uses aerodynamics to leviate the body

3. it made you superman

4. center of mass was below the pole

Q. A man is standing on a circular platform which is free to rotate about a fixed vertical axis. If the man starts moving on the periphery of the platform, the COM of the system (man + platform):

1. Is at the same position as before
2. Starts shifting towards periphery
3. Starts moving w.r.t. ground.
4. None of the above

Q.

The main reason that a Flosbury flop was so efficient was

1. center of mass was kept above the pole using less force

2. center of mass was below the pole

3. it uses aerodynamics to leviate the body

4. it made you superman

Q.

In which of the following cases center of mass is not inside the body

1. Semicircular disc with varying density

2. hollow metallic sphere

3. a Non uniform rod

4. a Flosbury flop

Q.

The main reason that a Flosbury flop was so efficient was

1. center of mass was kept above the pole using less force

2. center of mass was below the pole

3. it uses aerodynamics to leviate the body

4. it made you superman