Answer:
The force needed to slow down the car is, F = 67.5 N
Explanation:
Given data,
The mass of the car, m = 15 kg
The initial velocity of the car, V = 60 m/s
The final velocity of the car, v = 15 m/s
The time period of deceleration, t = 10 s
The difference in the momentum of the car is,
mV - mv = 15(60 - 15)
= 675 kg m/s
The rate of change in momentum of the car gives the force acting on it.
F = (mV - mu) / t
Substituting the values,
F = 675 / 10
= 67.5 N
Hence, the force needed to slow down the car is, F = 67.5 N
Answer: A
Explanation:
From the figure given as attachments, the error pointing upward signifies the incident ray while the one point downwards signifies the reflected ray.
One of the laws of reflection is stated that the angle of incidence is equal to the angle of reflection.
Since the two arrows are parallel to each other, then the mirror must be perpendicular to the two arrows. That is, the incident ray and the reflected ray must be perpendicular to the mirror.
Option A is the correct answer.
Explanation:
The total energy of the system remains conserved. It just converts from one form of energy to another.
The battery of the cell phone contains chemicals. As the electricity is passed through the cell phone, the electrical energy is converted to chemical energy. As she notices that the phone is warm and after the battery has been fully charged and the student unplugs her cell phone, the phone vibrates when a message arrives, this shows the conversion of chemical energy to mechanical energy, thermal energy etc.
Hence, we can say that the correct option is (b).
Answer:
Option C. ⁰₊₁e
Explanation:
From the question given above, the following data were obtained:
¹⁵₈O —> ¹⁵₇N + __
Let the unknown be ʸₓM
Thus, the equation becomes
¹⁵₈O —> ¹⁵₇N + ʸₓM
Next, we shall determine x, y and M. This can be obtained as follow:
8 = 7 + x
Collect like terms
8 – 7 = x
1 = x
x = 1
15 = 15 + y
Collect like terms
15 – 15 = y
0 = y
y = 0
ʸₓM => ⁰₁M => ⁰₊₁e
Therefore,
¹⁵₈O —> ¹⁵₇N + ʸₓM
¹⁵₈O —> ¹⁵₇N + ⁰₊₁e
