Mechanics | Relativity Answers

A rectangular fish tank measures 30 cm by 70 cm by 40 cm high. The tank is filled with water to a depth of 37 cm.
What is the pressure at the bottom due to the water?
What is the total force of the water on the bottom?

A spherical helium-filled balloon is used to lift a load of 5320 N (in addition to the weight of the helium). Suppose the density of the air is 1.27 kg/m3. Find the minumum necessary radius for the balloon

A hollow brass tube (diameter = 3.40 cm) is sealed at one end and loaded with lead shot to give a total mass of 0.191 kg. When the tube is floated in pure water, what is the depth, z, of its bottom end?

An ice skater spins about a vertical axis at an angular speed of 15 rad s−1 when her arms are
outstretched. She then quickly pulls her arms into her sides in a very small time interval so
that the frictional forces due to ice are negligible. Her initial moment of inertia about the
axis of rotation is 1.72 kg m2 and her final moment of inertia is 0.61 kg m2. What is the
change in her angular speed? What is the change in her kinetic energy? Explain this change
in kinetic energy.

At perihelion on feb 9,1986,Halley's comet was 8.79*10^7 km from the sun and was moving at a speed of 54.6 km/s relative to the sun.calculate its speed (a)when the comet was 1.16*10^8 km from the sun and (b) at its next apehelion in the year 2024,when the comet will be 5.28*1069 km from the sun.

a circular disc rotates on a thin air film with a period of 0.3s.Its moment of inertia about its axis of rotation is 0.06 kg m2.A small mass is dropped onto the disc and rotates with it.The moment of inertia of the mass about the axis of rotation is 0.04 kg m2.Determine the final period of the rotating disc and mass.

if the velocity of an object is zero is the acceleration also zero?motivate your answer

An object is moving along x-axis in such a way that its displacement is given by x=30+20t2 ,where x in meters and t in seconds .what will be initial and final velocities.

Lora (of mass 43.3 kg) is an expert skier. She
starts at 2.9 m/s at the top of the lynx run,
which is 106 m above the bottom.
What is her final kinetic energy at the bottom of the ski run?
Answer in units of j (due in 3 hours)

Calculate the acceleration of a body of mass 79 kg that has a force of 916 N acting on it at an angle of 29 degrees to the horizontal.