Answer:
False
Explanation:
The magnitude of any vector is given by,

The magnitude of anything is never negative. It can be even seen from the formula that the components are squared. A squared value can never be negative. Even if the component is negative the square will be always positive.
So, magnitude of the vector is <u>not</u> negative.
Answer:
3
Explanation:
The half-life of a radioactive isotope is the time it takes for the mass of the sample to halve.
This can be rewritten as follows:

where
m(t) is the mass of the sample at time t
m0 is the original mass of the sample
n is the number of half-lives that passed
We see that if we take n=3, the amount of original sample left is

So 3 (3 half-lives) is the correct answer.
Answer:
134.77 mm
Explanation:
Wave length of light λ = 599 x 10⁻⁹ m
Slit separation d = 20 x 10⁻⁶ m
Screen distance D = 3 m
Distance of second dark fringe from centre
= 1.5 x λ D / d
Putting the values given above
distance = 
= 134.77 x 10⁻³ m
= 134.77 mm.
Answer:
b) true. The jobs are equal
Explanation:
The work on a body is the scalar product of the force applied by the distance traveled.
W = F. d
Work is a scalar, the work equation can be developed
W = F d cos θ
Where θ is the angle between force and displacement
Let's apply these conditions to the exercise
a) False, if we see the expression d cosT is the projection of the displacement in the direction of the force, so there may be several displacement, but its projection is always the same
b) true. The jobs are equal dx = d cosθ
c) False, because the force is equal and the projection of displacement is the same
d) False, knowledge of T is not necessary because the projection of displacement is always the same
e) False mass is not in the definition of work