Answer:
7,546 J
Explanation:
recall that Potential energy is given by
P.E = mgΔh
where m = 70kg (given)
g = 9.8 m/s² (acceleration due to gravity)
Δh = change in height
= distance from top of building to top of car
= height of building - height of car
= (5+8) - 2
= 11m
substituting all these into the equation:
P.E = mgΔh
= 70 x 9.8 x 11
= 7,546 J
Answer:
The law of inertia relates to revolution of planets round the sun due to constant motion of the planets round the sun.
Explanation:
Law of inertia states that a body at rest or uniform motion will continue to be at rest or uniform motion unless it is acted upon by an external force.
The gravitational force keeps the planets revolving round the sun in a uniform motion, this will continue till infinity unless equal and opposite force acts on our planets.
Therefore, the law of inertia relates to revolution of planets round the sun due to constant motion of the planets round the sun.
Answer:
v_f =63 m/s
Explanation:
given,
starting force = 0 N
uniform rate increase to 36 N
time of action of Force = 35 s
mass of the body = 10 Kg
Speed of the object = ?
From the given data
if we plot F-t curve we will get a triangular shape
we know,
Impulse = Area between F-t curve
= (1/2) x base x height
= 0.5 x 35 x 36
= 630 N.s
now use Impulse-momentum theorem
Impulse = change in momentum
630 = 10 x (v_f - vi)
630 = 10 x (v_f - 0)
v_f =63 m/s
Speed of the object at 35 sec is equal to v_f =63 m/s
Answer: C is right
Explanation: Most of the sound waves are reflected back but waves passing opening will speread to all directions outside because of diffraction
