1. Using energy consideration and assuming negligible air resistance show that thrown from a bridge 20m above water with an initial velocity 15m/s strive the water with the speed of 24.4m/s independent of the direction thrown
3. What is the average watts consumption in watts of appliances by using an 5KW/hr of energy per day. How many joules of energy does this appliances consume in a year.
2.what is the watts of operating 3watts electric bulb for a year at the cost of electricity is Naira 32.5KW/hr
1. To solve this problem, we can use energy conservation principles. Let's assume that the potential energy at the top of the bridge is equal to zero. The total mechanical energy of the object at any point can be given as the sum of its potential energy and kinetic energy:
Initial mechanical energy = Potential energy + Kinetic energy
At the top of the bridge, the object only has potential energy, given by:
PE = mgh
Where m is the mass of the object, g is the acceleration due to gravity, and h is the height of the bridge (20m in this case).
At the bottom of the bridge, just before hitting the water, the object has both potential energy and kinetic energy. The potential energy at this point is zero, and the kinetic energy is given by:
KE = (1/2)mv^2
Where v is the final velocity of the object (24.4m/s in this case).
Since energy is conserved, the initial and final mechanical energies should be equal:
mgh = (1/2)mv^2
Mass cancels out, and we can solve for the final velocity:
24.4^2 = 2 * 9.8 * 20
Solving this equation, we find that the object will hit the water with a speed of 24.4 m/s, regardless of the direction it was thrown from.
2. To find the average power consumption in watts, we first need to convert the energy consumption from kilowatt-hours to joules.
Given that we have 5 kW/hr of energy consumed per day, we can calculate the energy consumption in joules using the following steps:
1 kilowatt-hour (kW/hr) = 3,600,000 joules
5 kW/hr = 5 * 3,600,000 joules = 18,000,000 joules (per day)
Next, to find the energy consumption in a year, we multiply the energy consumption per day by the number of days in a year (365):
18,000,000 joules * 365 days = 6,570,000,000 joules (per year)
So, the appliances consume 6,570,000,000 joules of energy in a year.
3. To find the watts consumed by a 3-watt electric bulb for a year, we need to calculate the energy consumption per year.
First, we convert the energy consumption from kilowatt-hours (kW/hr) to kilowatts (kW). The conversion factor is:
1 kilowatt-hour (kW/hr) = 1 kilowatt (kW) * 1 hour (hr)
So, the energy consumption of the bulb per year is calculated as:
3 watts * 24 hours/day * 365 days/year = 26,280 watt-hours (Wh)
Next, we need to convert the watt-hours to kilowatt-hours:
26,280 watt-hours / 1000 = 26.28 kilowatt-hours (kW/hr)
Finally, to determine the cost of electricity, we multiply the energy consumption in kilowatt-hours by the cost per kilowatt-hour (Naira 32.5):
26.28 kW/hr * Naira 32.5/kW/hr = Naira 856.20 (for the year)