Answer:
Opposite to the direction that you are pulling
Explanation:
Static friction acts in the opposite direction to the acceleration.
Kinetic friction acts in the opposite direction to the velocity.
Answer:
10 kg
Explanation:
Assuming a frictionless surface, then force F=ma where F is the applied force, m is the mass and a is acceleration. Making m the subject of the formula then 
Substituting 100 N for the applied force F and 10 m/s^2 for acceleration a then the value of m will be 
Therefore, in terms of kilograms, the bookshelf weighs 10 Kg
Answer:
62.5 %
Explanation:
Let the initial intensity of unpolarized light is Io.
After first polariser the intensity of light becomes I'.
So, 
Now it passes through another polariser. The angle between the first polariser and the second polariser is given by Ф. The intensity is I''.
According to the law of Malus

Here, Ф = 30 degree

The percentage change in the intensity is given by

= 62.5 %
Answer:
Explanation:
A lava lamp consists of oil, and wax in a glass, and a heat source (a light bulb) placed underneath the glass. When the lamp is turned on the bulb gets hot. As the bulb heats up some of the heat from the bulb is transferred to the glass by radiation.