Answer:
C.The car appears to be moving 30 km/hr in the opposite direction of the bus.
Explanation:
There are two reference systems involved in this situation:
- Reference system S: this is the reference system where velocities are measured with respect to the ground. In this reference system, the car is parked, so its velocity is
- Reference system S': this is the reference system moving with the bus. This reference system is moving with a velocity of with respect to the reference system S
Calling the velocity of the car in the reference system S', we have:
From which
and the negative sign means that a passanger in the bus observes the car moving in the opposite direction.
Answer:
117.83° F
Explanation:
Using Newton's Law of Cooling which can be expressed as:
The differential equation can be computed as:
where;
At the initial condition, T(0)= 350
replacing = 280 into (1)
Hence, the differential equation becomes:
when;
time (t) = 1 hour
T(1) = 250
Since;
k = -0.4418
Therefore;
T(t) = 70 + 280e^{(-0.4418)}t
After 4 hours, the temperature is:
T(t) = 70 + 280e^{(-0.4418)}4
T(4) = 117.83° F