Answer:
I=2 kg.m/s
Explanation:
The impulse is defined as the change of momentum:
![I=p_f-p_o\\I=m*v_f-m*v_o\\I=0.02kg*[(-60m/s)-40m/s]\\I=2kg.m/s](https://tex.z-dn.net/?f=I%3Dp_f-p_o%5C%5CI%3Dm%2Av_f-m%2Av_o%5C%5CI%3D0.02kg%2A%5B%28-60m%2Fs%29-40m%2Fs%5D%5C%5CI%3D2kg.m%2Fs)
We took the final velocity as negative since it is going on the opposite direction of the intial motion of the ball.
Answer:
a) 70 N, b) b. Each initially applied a force bigger than static friction to get the box moving and accelerating, then when the desired final speed was achieved they reduced the force to make the net force zero.
Explanation:
a) A constant speed means that magnitude of friction force is equal to the magnitude of the external force. The friction force is directly proportional to the normal force, which is equal to the weight of the box. Therefore, the magnitude of the force is 70 N.
b) Alice used initially a greater force to accelerate the box up to needed speed and later reduced the external force to keep speed constant. The right choice is option b.
Answer:
The Earth's magnetism is generated in the core, which is composed of iron that is constantly churning
Explanation:
Magnetic fields are produced by charges in motion, therefore by currents.
The outer core of the Earth consists mainly of melted iron that is in constant motion. This iron in motion actually acts as a giant current, and therefore it is responsible for the creation of the Earth's magnetic field.
The magnetic field of the Earth is very weak, in fact its magnitude is on average between 25 and 65 microtesla (for comparison, normal magnets can even produce magnetic fields of a few millitesla).
However, its role is very important for the Earth: in fact, it provides a shield that blocks most of the harmful radiation coming from the Sun.
Because of the hint we can conclude what equation we need to solve this problem. We have power and duration that means that we need to express energy:
1 joule = 1watt * 1 second
or
E (energy) = P (power) * t (time duration)
E = 350 * 30 = 10500 joules.
Answer:
150 N
Explanation:
Given that,
- Acceleration (a) = 3 m/s²
- Mass of the bike (m) = 50 kg
We are asked to calculate force required.
F = ma
F = (50 × 3) N
<u>F</u><u> </u><u>=</u><u> </u><u>1</u><u>5</u><u>0</u><u> </u><u>N</u>
