Answer:
Resistivity 
It depends upon cross sectional area and length of material
Explanation:
The resistance of any material is given by
, here
is the resistivity of material , l is length of material and A is cross sectional area
So resistivity 
So resistuivity of any material depends upon area of cross section and length of material
If cross sectional area will be more then resistivity will be more. And is length of the material will be more then resistivity will be less
Answer:
For part 1) correct answer is : a) SB=SN<VB=VN
For part 2) correct answer is : a) SB=SN<VB=VN
Explanation:
We will use the following formula of momentum
momentum after collision
=momentum before collision
=m*u1-(3*m*u2)
As we know u1 = u2 = 20 m/s
Hence,
-2*m*20 = 4*m*v
v = -10 m/s
v being the common velocity of the SUV and car after the collision
As we know that impulse is J = change in momentum = m*(v-u)
And u being initial velocity which is same for the SUV and car
non belted passengers collide with dashboards with a force which is called as a internal force and due to that internal forces the momentum remains constant heance impulse is also same experienced by seatbelted and non seat belated
As mass of SUV is 3 times the mass or car.
Hence the correct option is a) SB=SN<VB=VN
2) There is the same order of rant for force and impulse
As we know that impulse j = F*dt
Hence correct answer. is a) SB=SN<VB=VN
When a balloon is warmed by a lamp it just pops
Answer:
7.15 m/s
Explanation:
We use a frame of reference in which the origin is at the point where the trucck passed the car and that moment is t=0. The X axis of the frame of reference is in the direction the vehicles move.
The truck moves at constant speed, we can use the equation for position under constant speed:
Xt = X0 + v*t
The car is accelerating with constant acceleration, we can use this equation
Xc = X0 + V0*t + 1/2*a*t^2
We know that both vehicles will meet again at x = 578
Replacing this in the equation of the truck:
578 = 24 * t
We get the time when the car passes the truck
t = 578 / 24 = 24.08 s
Before replacing the values on the car equation, we rearrange it:
Xc = X0 + V0*t + 1/2*a*t^2
V0*t = Xc - 1/2*a*t^2
V0 = (Xc - 1/2*a*t^2)/t
Now we replace
V0 = (578 - 1/2*1.4*24.08^2) / 24.08 = 7.15 m/s