Mechanics | Relativity Answers

An experimental flywheel, used to store energy and replace a motor vehicle engine, is a solid disk of mass 200kg and radius 0,40m
a)What is the flywheel's rotational inertia?
b)when driving at 22,4m/s the fully energized flywheel is rotating at an angular speed of 3160 rad/s. What is the initial rotational kinetic energy of the flywheel?
c)If the total mass of the car is 1000kg find the ratio of the initial rotational kinetic energy of the flywheel to translational kinetic energy of the car.
d)If the force of air resistance on the car is 670N how far can the car travel at a speed of 22,4m/s with the initial stored energy?(Ignore losses of mechanical energy due to means other than air resistance)

a car has a drag coefficient Cd=0.30, a frontal area of A = 1.9 meter square, a mass 1.2 tonnes and a coefficient of rolling resistance, Cr,= 0.012. it is travelling up a hill with a slope of 1 in 20 at 110 kph.
at what rate it is doing work against gravity(i.e. at what rate is it increasing its gravitational potential energy)?
Pg=_______kW.
(a 1:20 grade means that it rises 1m for every 20 m travelled along the road: sin(theta) = 1/20.)

at the radius of the earth's orbit, the intensity of the sunlight is I=1.4kW/m².(this means that 1.4 kW/m² passes thorough 1 square metre at right angles to the sun's rays.) the solar array consist of 10 panels, each with area A= 1.6m². under optional conditions -with the sun at the right angles to the array and no clouds in the sky-the array produces Power output =2.3kW. what is the efficiency of the array? (power output/power input-------%)

I drag a mass m=21 kg in a straight line, along a horizontal surface, a distance D= 23m .I drag it at constant speed v=0.90m/s in a straight line using a horizontal force.the coefficient of static friction is 1.2 and coefficient of kinetic friction is 1.1.How much work do I do in joules?

The amplitude of a spring-mass system in simple harmonic motion is 8 m. Calculate the value of
displacement x where the magnitude of the velocity is 9/16 of its maximum value.

A volley ball is thrown straight upward on the moon with an initial speed of 30 m/s .Calculate: (a) The maximum height reached by the ball. (b) The time taken to reach that height. (c) Its velocity 20s after it is thrown. (d) When the ball’s height is 50m. (g = 1.60m/s2 on the moon).

A copper calorimeter of mass 150g was half-filled with water of mass 300g and temperature 0°C. 5g of ice at 0°C was added to the content, later some quantity of steam was passed into the mixture and the temperature rose by 20°C. Calculate the quantity of steam added? (Specific latent heat of vaporization of steam = 2260000j/kg, specific heat of copper = 400J/kg/K)

7. A 65 kg trampoline artist jumps vertically upward from the top of platform with speed of
5.0 m/s .
a) How fast is he going as he lands on the trampoline 3.0 m below?
b) If the trampoline behaves like a spring with spring stiffness constant 6.2 x 10 4 N/m.
How far does he depress it?

4. A geosynchronous satellite is one that stays above the same point on earth. Which is
possible only if it is above a point on the equator. Such Satellites are used for TV and
radio transmission, for weather forecasting, and as communication relays.
Determine:
a) the height above the earth’s surface such a satellite must orbit
b) Satellite’s speed
c) Compare to the speed of a satellite orbiting 200 km above earth surface.

3. A 0.45 kg ball attached to the end of horizontal cord is rotated in a circle of radius 1.3 m
on frictionless horizontal surface. If the cord will break when the tension in it exceeds 75
N. what is the maximum speed the ball can have?