Some examples of when friction is helpful are: to help the movement of tires. When you walk, and also, when you erase. :)
Answer:
Resistance to electrical currents
Explanation:
Conductors have low resistance to electrical currents, and are used to "conduct" the flow of electricity.
Insulators have very high resistance and are used to protect us from the flow of electricity.
Answer:
m = 35 g
Explanation:
The specific heat of a material can be calculated by the following formula:
where,
C = Specific Heat of Wax = 220 J/g
Q = Amount of Heat Supplied by the Heater = 7700 J
m = mass of wax melted = ?
Therefore,
<u>m = 35 g </u>
As per the question Bob drops the bag full with feathers from the top of the building.
The mass of the bag(m)= 1.0 lb
Let the air resistance is neglected.As the bag is under free fall ,hence the only force that acts on the bag is the force of gravity which is in vertical downward direction.
Here the acceleration produced on bag due to the free fall will be nothing else except the acceleration due to gravity i.e g =9.8 m/s^2
Here we are asked to calculate the distance travelled by the bag at the instant 1.5 s
Hence time t= 1.5 s
From equation of kinematics we know that -
S=ut + 0.5at^2 [ here S is the distance travelled]
For motion under free fall initial velocity (u)=0.
Hence S= 0×1.5+{0.5×(-9.8)×(1.5)^2}
⇒ -S =0-11.025 m
⇒ S= 11.025 m
=11 m
Here the negative sign is taken only due to the vertical downward motion of the body .we may take is positive depending on our frame of reference .
Hence the correct option is B.
