Sound waves can be used in a similar way to "see" things. After turning on a sound source, we can look at the pattern of reflected sound waves that bounce back to us. Our own ears and brain don't process sound into mental pictures.
Explanation:
u=54 km/h
54*5/18=15 m/s
v=0m/s
t=?
acceleration=-0.5m/s^2
we know that a=v-u/t
so,
t=v-u/a
t=15-0/0.5
=15/0.5
=30
therefore, the time is 30 second
Hope this answer helps you..
Answer:
0.01606 Newtons
Explanation:
r = Distance between the asteroid and Sally = 17000000 m
m₁ = Mass of the asteroid = 8.7× 10²⁰ kg
m₂ = Mass of Sally = 80 kg
G = Gravitational constant = 6.67 × 10⁻¹¹ m³/kgs²
From Newton's Universal law of gravity

The force Sally experiences is 0.01606 Newtons
Despite current has a magnitude and a direction, like vectors, it is a scalar because it doesn't obey laws of vector addition. For instance, if we consider a junction of

in a circuit, and two currents entering this junction, we know that the resultant current is just the algebraic sum of the two currents, not the vector sum, so it is not a vector quantity.