Answer:
a.) F = 3515 N
b.) F = 140600 N
Explanation: given that the
Mass M = 74kg
Initial velocity U = 7.6 m/s
Time t = 0.16 s
Force F = change in momentum ÷ time
F = (74×7.6)/0.16
F = 3515 N
b.) If Logan had hit the concrete wall moving at the same speed, his momentum would have been reduced to zero in 0.0080 seconds
Change in momentum = 74×7.6 + 74×7.6
Change in momentum = 562.4 + 562.4 = 1124.8 kgm/s
F = 1124.8/0.0080 = 140600 N
You first us 1/2(mv^2) to solve for the potential energy and then put that in to PE=m*g*h and solve for hight
Answer:
b) It is impossible to tell without knowing the masses.
Explanation:
The temperature change of a substance when it receives/gives off a certain amount of heat Q is given by

where
Q is the amount of heat
m is the mass of the substance
Cs is the specific heat capacity of the substance
In this case, we have a hot piece of aluminum in contact with a cold piece of copper: the amount of heat given off by the aluminum is equal to the amount of heat absorbed by the copper, so Q is the same for the two substances. However, we see that the temperature change of the two substances depends on two other factors: the mass, m, and the specific heat, Cs. So, since we know only the specific heat of the two substances, but not their mass, we can't tell which object will experience the greater temperature change.
Answer:
57.6Joules
Explanation:
Rotational kinetic energy of a body can be determined using the expression
Rotational kinetic energy = 1/2Iω²where;
I is the moment of inertia around axis of rotation. = 5kgm/s²
ω is the angular velocity = ?
Note that torque (T) = I¶ where;
¶ is the angular acceleration.
I is the moment of inertia
¶ = T/I
¶ = 3.0/5.0
¶ = 0.6rad/s²
Angular acceleration (¶) = ∆ω/∆t
∆ω = ¶∆t
ω = 0.6×8
ω = 4.8rad/s
Therefore, rotational kinetic energy = 1/2×5×4.8²
= 5×4.8×2.4
= 57.6Joules
The strength of the magnetic field is 
Explanation:
According to Faraday's Law, the magnitude of the induced emf in the coil is equal to the rate of changeof the flux linkage through the coil:
(1)
where
N = 505 is the number of turns in the coil
is the change in magnetic flux through the coil
is the time interval

The coil is rotated from a position perpendicular to the Earth's magnetic field to a position parallel to it, so the final flux is zero, and the magnitude of the flux change is simply equal to the initial flux:

where
B is the strength of the magnetic field
A is the area of the coil
is the angle between the normal to the coil and the field
The area of the coil can be written as

where
is its radius
Substituting everything into eq.(1) and solving for B, we find:

Learn more about magnetic fields:
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