Answer:
0.130
Explanation:
From the given data, the coefficient of static friction for each trial are:
1. 0.053
2. 0.081
3. 0.118
4. 0.149
5. 0.180
6. 0.198
The sum of the coefficient of static friction = 0.053 + 0.081 + 0.118 + 0.149 + 0.180 + 0.198
= 0.779
So that;
the average coefficient of static friction = 
= 
= 0.12983
The average coefficient of static friction is 0.130
The velocity of tennis racket after collision is 14.96m/s
<u>Explanation:</u>
Given-
Mass, m = 0.311kg
u1 = 30.3m/s
m2 = 0.057kg
u2 = 19.2m/s
Since m2 is moving in opposite direction, u2 = -19.2m/s
Velocity of m1 after collision = ?
Let the velocity of m1 after collision be v
After collision the momentum is conserved.
Therefore,
m1u1 - m2u2 = m1v1 + m2v2


Therefore, the velocity of tennis racket after collision is 14.96m/s
Answer:
f=8.219*10^{8}Hz
Explanation:
We are going to use the formula v=fλ
Where v= velocity of radio waves
f= frequency
λ= wavelength of wave
- radio waves are electromagnetic waves and as such they have the speed of light which is 3*10^{8}m/s.
- also when a wave travels from one medium to another, the wavelength changes while the frequency remains the same.
- calculating for the frequency of the wave in air also gives us the frequency in the window glass.
f=\frac{v}{λ}
v=3*10^{8}m/s.
λ=36.5 cm = 36.5/100= 0.365m
f=\frac{3*10^{8}m/s.}{0.365m}
f=8.219*10^{8}Hz
Answer:

Explanation:
Given:
- mass of car,

- distance of skidding after the application of brakes,

- coefficient of kinetic friction,

<u>So, the energy dissipated during the skidding of car:</u>
<em>Frictional force:</em>

where N = normal reaction by ground on the car


<em>Now from the work-energy equivalence:</em>


is the dissipated energy.
Answer: machine's efficiency = 82.2%
Explanation:
Efficiency of a machine is the capability of a machine to convert input to output without waste.
It can be expressed as
Efficiency = output/ input × 100%
Output = 7,023N
Imput = 8,542N
Efficiency = 7,023N/8,542N × 100%
Efficiency = 82.2%