Answer:
0.4
Explanation:
F-Fr=ma where F is applied force, Fr is friction, m is mass and a is acceleration.
Since the mass is moving with a constant velocity, there's no acceleration hence
where N is the weight of object and \mu is coefficient of kinetic friction.
![F=\mu N and making [tex]\mu](https://tex.z-dn.net/?f=F%3D%5Cmu%20N%20and%20making%20%5Btex%5D%5Cmu)
the subject
Substituting F for 8 N and N for 20 N
Therefore, coefficient of kinetic friction is 0.4
Answer:
1.549 m
Explanation:
Given:
The radius of the circular board, r = 2 m
The probability of hitting the red is given as 0.6
Now, this probability of hitting the red can be conclude as
0.6 = (Area of red)/ (Total area of the board)
Total area of the board = πr² = π × 2²
let the radius of the red area be R
thus, area of red circle, = πR²
on substituting the value of the area, we have
0.6 = (πR²)/ (π × 2²)
or
R² = 2.4
or
R = 1.549 m
Thus, the radius of the red circle is 1.549 m
The kinetic energy of any moving object is
K.E. = (1/2) (mass) (speed)² .
To use this simple formula, the 'mass' has to be in kilograms,
and the 'speed' has to be in meters-per-second.
You can see that we have a slight problem that has to be cleaned up:
The speed in the question is given in "kilometers per hour", but we'll
need it in "meters per second". So let's convert that right now:
(600 km/hour) x (1 hour / 3600 seconds) x (1000 meters / km)
= (600 x 1 x 1000 / 3600) (km-hour-meters / hour-second-km)
= 166.67 meters/second .
Now we're ready to plug numbers into the formula for K.E.
(1/2) (mass) (speed)²
= (1/2) (80,000 kg) (166.67 m/s)²
= (40,000 kg) (27,777.8 m²/s²)
= 1,111,111,111 kg-m²/s²
= 1.1... x 10⁹ Joules (choice D)
Answer: D
Explanation: Resistance of current in a wire is directly proportional to the length of the wire and inversely proportional to the cross - sectional area of the wire. That is,
R = (rho × L)/A
Where
L = length of the wire
A = cross sectional Area of the wire
rho = resistivity = proportionality constant which depends on the quality of the wire.
Therefore, Resistance and resistivity are related by a:
proportionality constant dependent on the identity of the material.
