Answer:
This is because below 4°c, water unlike other materials becomes less dense when it's temperature is further lowered.
Explanation:
Due to the unusual nature of water; at about 4°c, the behavior of the density of water in relation to its temperature reverses. This means that water becomes less dense as it becomes colder below 4°c. The colder parts therefore floats to the top of the water body while the warmer part sinks allowing the top to freeze and the remaining body below to remain in its liquid state.
The freezing of the top of the lake alone protects the remaining depth of water from freezing by acting as an insulator and preventing further heat loss from the water to the ambient space. If this had not been the case, and water froze all through, marine lives will freeze to death and it will be more difficult to melt the ice come the next summer.
This behavior is due to the hydrogen bonding of the water molecules.
Answer:
Explanation:
The resultant force F
where 
is eastward force, 
is force directed towards the North
F=62573.2 N
The magnitude of acceleration of sailboat is given by
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.
Answer:
Explanation:
Force = Mass * acceleration due to gravity.
Given
Mass of the paratrooper = 57kg
Acceleration due to gravity = 9.81m/s²
Required
Force pulling him down
Substitute unto formula;
F = 57 * 9.81
Force = 559.17 N
Hence the force pulling him down is 559.17N
Answer:
d = Δv(t2-t1)
Explanation:
Speed is defined as the change of displacement with respect to time. It is expressed as shown;
Speed = change in displacement/change in time
Δv = d/Δt
d = Δv*Δt
d = ΔvΔt
Δt = t2-t1
d = Δv(t2-t1)
Δv is the change in rate of speed
Δt = change in time
The correct expression for the displacement of the car during this motion is d = Δv(t2-t1)
