Answer:
Work done by the gardner is 500 J
Explanation:
As we know that the gardner apply force perpendicular upward by magnitude 300 N and along the floor horizontal force is 100 N
so we have

now the displacement of the gardner along the floor is

now work done is given as

so we have


<span>A bike is compound machine.This means that it is made up of a bunch of different simple machines. Screws are used to hold the pieces together. The wheel of a bicycle is a wheel and axle. The pedals are also examples of this simple machine. The pedals are attached to a lever that turns a pulley.</span>
As we know that friction force on box is given by

here we know that

here we have
m = 12 kg

so now we have

now we will have


so it required minimum 49 N(approx) force to move the block
A becomes positive, while b is now negative. Basically, electrons are negative particles. If they go to somewhere, they make the somewhere they go to negative.
Answer:
The frequency of these waves is 
Explanation:
Given that,
Wavelength = 6.6 km
Distance = 8810 km
Time t = 8.67 hr
We need to calculate the velocity of sound
Using formula of velocity

Where, D = distance
T = time
Put the value into the formula


We need to calculate the frequency
Using formula of frequency


Put the value into the formula





Hence, The frequency of these waves is 