Answer:
(a) 348.4 m
(b) 256.7 m/s
(c) 127.2 m/s^2
Explanation:
(a) at t = 4 s
x = 2.3 x 4 + 5.3 x 4 x 4 x 4
x = 348.4 m
(b) The derivative of displacement function gives the value of instantaneous velocity.
So, v = dx / dt = 2.3 + 5.3 x 3 x t^2
v = 2.3 + 15.9 t^2
Put t = 4 s
So, v = 2.3 + 15.9 x 4 x 4
v = 256.7 m/s
(c) The derivative of velocity function with respect to time gives the value of instantaneous acceleration.
So, a = dv / dt = 5.3 x 3 x 2 x t
a = 31.8 t
Put t = 4 s
a = 31.8 x 4 = 127.2 m/s^2
Explanation:
Red, green, and blue are therefore called additive primaries of light. ... When you block two lights, you see a shadow of the third color—for example, block the red and green lights and you get a blue shadow. If you block only one of the lights, you get a shadow whose color is a mixture of the other two.
First, your definition of a shadow is incorrect. A shadow is an area that receives less light than its surroundings because a specific source of light is blocked by whatever is "casting" the shadow. Your example of being outside reveals this. The sky and everything around you in the environment (unless you are surrounded by pitch black buildings) is sending more than enough light into your shadow, to reveal the pen to your eyes. The sky itself diffuses the sunlight everywhere, and the clouds reflect plenty of light when they are not directly in front of the Sun.
If you are indoors and have two light bulbs, you can throw two shadows at the same time, possibly of different darknesses, depending on the brightness of the light bulbs.
It can take a lot of work to get a room pitch black. One little hole or crack in some heavy window curtains can be enough to illuminate the room. There are very few perfectly dark shadows.
Answer:
when the body is resting N = 246.96 N
when the body is resting on a tilted surface N = 212.12 N.
when the body is in a elevator N = 317.036 N
Explanation:
when the block is resting on a stationary surface the normal force is balanced by the weight of the body.
weight of the body = mg = 25.2×9.8 = 246.96 N
therefore normal force = 246.98 N.
when the block is resting on a tilted surface the normal force will be balanced by the 
component of the weight where Ф is the angle of inclination.
therefore N = mg
N= 212.12 N.
when the block is resting on a elevator that is accelerated upward the normal force will be the sum of weight and force due to acceleration ma
therefore N = 246.98 + 25.2×2.78
N = 317.036 N
Static friction is the friction between an object at rest and the surface on which it is resting on.
Kinetic friction is the friction between a moving object and the surface on which it moves.
Hopefully you understood and this helps :)
The amount of Li present to start the reaction is 55.18g
<u>Explanation:</u>
2Li + Br₂ → 2LiBr
Molecular weight of Br₂ = 159.808 g/mol
Mass of Br₂ present = 225 g
Moles of Br₂ present during the reaction = 225 / 159.808
m = 1.4
Molecular weight of LiBr = 86.845 g/mol
Mass of LiBr formed = 690 g
moles of LiBr produced = 690 / 86.845
m(LiBr) = 7.95
According to the balanced equation, 2 molecules of Li reacts to for 2 molecule of LiBr
So, 7.95 moles of LiBr would require 7.95 moles of Li
The molecular weight of Li is 6.941 g/mol
Thus, the amount of lithium present to start the reaction is
Therefore, the amount of Li present to start the reaction is 55.18g
