Answer:
Part a)
Part B)
Explanation:
Part a)
Average power is rate of energy consumption
So it is given as
Part b)
If the efficiency is given as
%
so we know that 20% of total energy consumed is converted into output work
So total power consumed here will be given as
Energy consumed by him
now we know that 1 g fat will release 9 Calories energy
So we have
so to consume 1000 g of fat we need to release total energy
so total number of times
We can do this with the conservation of momentum. The fact it is elastic means no KE is lost so we don't have to worry about the loss due to sound energy etc.
Firstly, let's calculate the momentum of both objects using p=mv:
Object 1:
p = 0.75 x 8.5 = 6.375 kgm/s
Object 2 (we will make this one negative as it is travelling in the opposite direction):
p = 0.65 x -(7.2) = -4.68 kgm/s
Based on this we know that the momentum is going to be in the direction of object one, and will be 6.375-4.68=1.695 kgm/s
Substituting this into p=mv again:
1.695 = (0.75+0.65) x v
Note I assume here the objects stick together, it doesn't specify - it should!
1.695 = 1.4v
v=1.695/1.4 = 1.2 m/s to the right (to 2sf)
The speed of light in glass is slower than the speed of light through space.
Answer:
1) True: Spring A is stiffer than B (kA > kB). Less work must be expended on spring A if both springs are stretched by the same amount.
2) False: The kinetic energy of an object depends on the direction of the motion involved.
3) True: The work done to raise a box onto a platform does not depend on how fast it is raised.
4) True: The friction force is a non-conservative force.
5) True: The kinetic energy can be negative.
6) False: The kinetic energy does not depend on the reference frame of the observer.
7) False: Work can be done in the absence of motion.
8) False: If the moon revolves around the earth in a perfectly circular orbit, then the earth does do work on the moon.
