¿Es esta una pregunta verdadera o falsa? Por cierto, no hay mucha gente que hable español en esta aplicación, así que buena suerte.
Answer:
The magnitude of the frictional force is 
Explanation:
From the question we are told that
The force exerted on the box is 
Generally for the box to remain at rest then it means that the frictional force is greater than or equal to the force applied to move it i.e
=>
Answer:
A calorie is defined as the amount of energy needed to raise the temperature of one gram of water one degree Celsius.
Explanation:
The other unit used to measure heat is the joule. The joule is the SI (System International) unit
Answer:
Let’s assume that the projectile has the same initial velocity in both cases. It is necessary to find that velocity.
u = u[x]i +u[y]j = [u cos 15]i + [u sin 15]j
The p.v. ; s = s[x]i +s[y]j , get the time of flight by letting s[y]=0
s[y] = [u(y)].t -[1/2]gt^2 =0 , so t = 2u[y]/g
t = [ 2 u sin 15]/g eq 1
s[x] = [ u cos 15] .t eq 2 , substitute in eq q into eq2
range =r = [ u cos 15 ][ 2u sin 15 ]/g =[u^2/g][ 2 sin 15 . cos 15],
r =[ u^2 sin 30]/g =1.5 km
( from this we see that ,in general, r = [u^2 .sin (2a)]/g
u^2 = [ 3g] , eq 1
Now do the 2 nd part
r[2] = [u^2 sin (2a)]/g , eq 2 Let a =45 and substitute eq 1 into eq 2
r[2] = [3g sin 90]/g
r[2] =3 km.
Explanation:
