You have to solve this by using the equations of motion:
u=3
v=0
s=2.5
a=?
v^2=u^2+2as
0=9+5s
Giving a=-1.8m/s^2
Then using the equation:
F=ma
F is the frictional force as there is no other force acting and its negative as its in the opposite direction to the direction of motion.
-F=25(-1.8)
F=45N
Then use the formula:
F=uR
Where u is the coefficient of friction, R is the normal force and F is the frictional force.
45=u(25g)
45=u(25*10)
Therefore, the coefficient of friction is 0.18
Hope that helps
Answer:
7800 J
Explanation:
Heat needed = mass of copper x specific heat of copper x change in temperature
Change in temperature = 30ºC - 20ºC = 10ºC
Specific heat of copper = 390 J/kgºC
Mass of copper = 2 Kg
Substituting the given values in above equation, we get –
Heat needed = 2 Kg x 390 J/kgºC x 10ºC
= 7800 J
Answer:
C. second law of thermodynamics.
Explanation:
One of the consequences of this law is that there is no process of energy transformation 100% efficient. Some energy will always be lost in in the form of heat, which will be used to raise the temperature of some engine component, or its surroundings, and we will not be able to take advantage of it.
Answer:
v₀ = 60.38 mi / h
With this stopping distance, the starting speed should have been 60.38 mi/h, which is much higher than the maximum speed allowed.
Explanation:
For this exercise let's start by using Newton's second law
Y axis
N-W = 0
N = W
X axis
fr = m a
the expression for the friction force is
fr = μ N
we substitute
μ mg = m a
μ g = a
calculate us
a = 0.620 9.8
a = 6.076 m / s²
now we can use the kinematics relations
v² = v₀² - 2 a x
suppose v = 0
v₀ = 
Ra 2ax
let's calculate
v₀ = 
v₀ = 27.00 m / s
let's slow down to the english system
v₀ = 27.0 m / s (3.28 ft / 1m) (1 mile / 5280 ft) (3600s / 1h)
v₀ = 60.38 mi / h
With this stopping distance, the starting speed should have been 60.38 mi/h, which is much higher than the maximum speed allowed.
