From laws of motion:
Where S is the distance/displacement (as you would call it) which is unknown
v = final velocity which is 0m/s (this is because the car stops)
u = initial velocity which is 36m/s (from the data given)
t = time taken for the distance to be covered and it is 6s
Substitute the values, hence:
But this is merely the distance he travelled in the 6 seconds he was trying to stop the car.
Therefore, the distance between the car and the cows = 160-108
Distance = 52m
Answer:
<em>U = 66,150 J</em>
Explanation:
<u>Gravitational Potential Energy</u>
Gravitational potential energy is the energy stored in an object because of its vertical position or height in a gravitational field.
It can be calculated with the equation:
U=m.g.h
Where m is the mass of the object, h is the height with respect to a fixed reference, and g is the acceleration of gravity or .
The child of mass m=45 Kg is perched above a h=150 m ravine. His gravitational potential energy is:
U = 66,150 J
Recall Newton's second law:
F = ma
F is the force exerted on the object.
m is the mass of the object.
a is the acceleration of the object.
Given values:
F = 75 N
m = 15 kg
Substitute the terms in the equation with the given values and solve for a:
75 = 15×a
<h3>a = m/s²</h3>
Answer is: 124135 J.
m(water) = 55g.
T(water) = 100°C.
Q = ?
Q - heat needed to convert water to steam.
∆Hvap = 2257 J/g
∆Hvap - enthalpy of vaporization is the amount of energy <span> needed to transform the liquid substance into a gas.
Q = </span>∆Hvap · m(water) = 2257 J/g · 55g = 124135 J.
Explanation:
Problem 2.5, mixing dough.
Please note dimensional units and standard formulas for energies.
Input:
Electrical energy = VIT = 110 V * 1.5 A * 5 min. * 60 s/min = 49500 joules = 49.5 kJ
Output:
Warming of dough = mCΔT = 1 kg * 4.2 kJ/(kg*K) * 5 deg.K = 21 kJ
Dissipation of energy = remainder of input energy = (49.5-21) kJ = 28.5 kJ
Fraction of energy converted to energy of dough = 21 kJ / 49.5 kJ
= forty-two percent (to the nearest percent)
The last item, dissipation of energy could be attributed to:
1. Loss in efficiency of mixer in the form of mechanical friction, heating up due to resistance of motor circuit, etc.
2. Loss in mechanical mixing of dough due to friction between mixer paddle and dough in the form of heat, part of which stays with dough (thus heating up of dough), and the remainder heats up the dough container, loss of heat to environment, air, heat of vaporization of water content of dough, etc.