Newton's first law states that an object traveling with a constant velocity will remain traveling at a constant velocity unless
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Answer:
105 m/s
Explanation:
Given that the speed of train A, = 45 m/s from west to east.
Speed of train B, = 60 m/s from east to west.
Train B is moving in the opposite direction with respect to the speed of train A. Assuming that the speed from east to west direction is positive.
So, the speed of train A from east to west= - 45 m/s
The speed of train B w.r.t train A m/s
Hence, the speed of train B w.r.t train A is 105 m/s from east to west.
A. 0.77 A
Using the relationship:
where P is the power, V is the voltage, and R the resistance, we can find the resistance of each bulb.
For the first light bulb, P = 60 W and V = 120 V, so the resistance is
For the second light bulb, P = 200 W and V = 120 V, so the resistance is
The two light bulbs are connected in series, so their equivalent resistance is
The two light bulbs are connected to a voltage of
V = 240 V
So we can find the current through the two bulbs by using Ohm's law:
B. 142.3 W
The power dissipated in the first bulb is given by:
where
I = 0.77 A is the current
is the resistance of the bulb
Substituting numbers, we get
C. 42.7 W
The power dissipated in the second bulb is given by:
where
I = 0.77 A is the current
is the resistance of the bulb
Substituting numbers, we get
D. The 60-W bulb burns out very quickly
The power dissipated by the resistance of each light bulb is equal to:
where
E is the amount of energy dissipated
t is the time interval
From part B and C we see that the 60 W bulb dissipates more power (142.3 W) than the 200-W bulb (42.7 W). This means that the first bulb dissipates energy faster than the second bulb, so it also burns out faster.
Answer:
Explanation:
<u>Motion with Constant Acceleration</u>
A body moves with constant acceleration when the speed changes uniformly in time. The equation used to find the final speed vf is
Where vo is the initial speed, a is the acceleration, and t is the time.
The cyclist has an initial speed of vo=10 miles/hour and ends up at vf=20 miles/hour in t=5 seconds.
Both speeds are given in miles/hour and we must convert it to m/s:
1 mile/hour = 0.44704 m/s
10 mile/hour = 4.47 m/s
20 mile/hour = 8.94 m/s
The acceleration is calculated by solving for a: