Answer: k = 5.4kg/m
where m is the mass of the crate.
Explanation:
The force of kinetic friction is described by the equation:
Ff = k*N
in the opposite direction in wich the object moves, where k is the coefficient of kinetic friction and N is the normal force, that is equal to the weight of the crate. N = m*g where m is the mass of the crate and g is the gravitational acceleration.
If the crate keeps moving with constant velocity, this means that the crate is not accelerating so there is no net force applied on the crate. Then the friction force should be equal in magnitude to the horizontal force of 53N (but with different sign)
then we have:
k*m*g = 53N
k*m = 53N/9.8m/s^2 = 5.4kg
k = 5.4kg/m
In the question we do not have the mass of the crate, so you must put the value in that equation to get the value of k.
Answer:
A. a motor
Explanation:
A motor is an electrical device or machine that converts electrical energy into mechanical energy. That is, a motor takes electrical energy to produce motion. There are different types of motors such as DC motor, induction motor and so on.
When electrical current flows through a coil, a magnetic flux is been produced, therefore when a rotating power source is supplied to coil of a motor, a magnetic field is produced which causes torque.
If it takes 1 year for this crab to travel 5,70km
Then, it will takes approximatly 1000/5,70 = 175 years to travel 1000 km
Answer:
8.79*10^6 rad/s
Explanation:
To find the frequency of the circular orbit for an electron you use the following expression, for the radius of the trajectory of an electron, that travels trough a constant magnetic field:
(1)
r: radius of the trajectory
m: mass of the electron = 9.1*10^-31 kg
v: speed of the electron = 1.0*10^6 m/s
q: charge of the electron = 1.6*10^-19 C
B: magnitude of the magnetic field = 5.0*10^-5 T
You use the fact that the angular frequency in a circular motion is given by:
Then, you solve the equation (1) in order to obtain v/r:
Finally, you replace the values of the parameters:
hence, the angular frequency is 8.79*10^6 rad/s
The frequency is:
We could use the change of pressure to calculate for the height climbed by the mountain hiker. The change of pressure is given by
p = rho * g * h, where p is the change of pressure, rho is the air density, g is the acceleration due to gravity, and h is the height.
Using the conversion 1 mbar = 100 Pa,
(930 - 780)(100) = (1.20)(9.80)h
15000 = 1.20*9.80*h
h = 1.28 km
