Answer: first and third.
Explanation:
An equation is dimensionally correct if the units are the same in both sides of the equation.
first, let's define the units used:
{m} = kg
{v} = m/s
{F} = kg*m/s^2
{x} = m
{t} = s
{a} = m/s^2
Now, let's analyze each option:
1) m*v/t = F
in the left side the units are:
{m}*{v}/{t} = kg*(m/s)*(1/s) = kg*m/s^2
And as is written above, these are the units of F, so this is correct.
2) x*v^2 = F*(x^3/x^2)
This is more trivial, in the right side we can see an F, that has mass units (kg) and in the left side we have x and v, and we know that none of these have mass units, so this expression is not correct.
3) xt= vt^2+at^3
the units in the right side are:
{x}*{t] = m*s
in the right side are:
{v}*{t}^2 + {a}*{t}^2 = (m/s)*s^2 + (m/s^2)*s^3 = m*s + m*s
So in both sides of the equation we have the same units, then this equation is dimensionally correct.
Answer:
Explanation:
For lens A
object distance u = - 13.1 cm , focal length f = 6.19 cm
From lens formula
1/v - 1/u = 1/f
1 / v + 1/13.1 = 1/6.19
1/v = 1/6.19 - 1/13.1
= .16155 - .07633
= .08522
v = 11.7 3 cm
For lens B
object distance u = - ( 55.7 - 11.73) = - 43.97 cm , focal length f = 27.9 cm
From lens formula
1/v - 1/u = 1/f
1 / v + 1/43.97 = 1/27.9
1/v = 1/27.9 - 1/43.97
= .03584 - .022742
= .013098
v = 76.35 cm
Image will be formed 76.35 cm behind lens B .
magnification of lens system
= m₁ x m₂ , m₁ is magnification by lens A and m₂ is magnification by lens B
= (11.73 / 13.1) x (76.35 / 43.97)
= .8954 x 1.73
= 1.5547
size of image = total magnification x size of object
= 1.5547 x 6.47
= 10 cm approx. The first image will be real and inverted and second image will be erect with respect to object.
Answer:
The recoil speed of the man and rifle is 
.
Explanation:
The expression for the force in terms of mg is as follows;
F=mg
Here, m is the mass and acceleration due to gravity.
Rearrange the expression for mass.
Calculate the combined mass of the man and rifle.
Put 
.
The expression for the conservation of momentum is as follows as;
Here, 
is the mass of the man and rifle, 
is the mass of the rifle,
are the initial velocities of the man and bullet and 
are the final velocities of the man and rifle and rifle.
It is given in the problem that a rifle with a weight of 25 N fires a 4.5-g bullet with a speed of 240 m/s.
Convert mass of rifle from gram to kilogram.
Put , , 
, 
and 
.
Therefore, the recoil speed of the man and rifle is .
Answer:
( 1000 × 4 = 4,000) (800×3= 2400) (800×2=1600) the answer is 1600 hope it helps
Answer:The distance and magnitude of displacement are sometimes equal." Jafar is correct. The distance traveled and the magnitude of displacement are equal if and only if the path is a straight line in one direction.
Explanation:
