First we gotta use an equation of motion:

Our vertical distance d= 100 m, initial vertical speed u = 0 m/s (because velocity is fully horizontal), and vertical acceleration a = 9.8 m/s2 because of gravity. Let's plug it all in!

Now we just need to solve for t:

Hit the calculators, and you'll get 4.5 seconds!
Answer:
C) Use a battery with more voltage.
Explanation:
The equation for the magnetic field around a coil is given by,
B = μ₀NI
where,
B = Magnetic flux density
μ₀ = permeability
N = number of turns per meter
I = Current in the wire
So when using a higher voltage battery, more current passes through the battery as resistance of the wire remains the same.
Answer:
120 miles per hour.
Explanation:
We need to find the time it takes my parents to drive home from the cottage. Since my father drives at 60 miles per hour, and the cottage is 240 miles from our home, and distance = speed × time. So, time = distance/speed = 240 mi/60 mi/h = 4 h.
So, it will take my father 4 hours to drive home from the cottage.
Since I have 2 hours to prepare for the party, the time left for me to drive to the cottage is 4 - 2 hrs = 2 hrs.
So, I'm supposed to drive to the cottage in at most 2 hours.
The speed at which I must drive in this time period is thus, speed = distance/time = 240 miles/2 hours = 120 miles per hour.
So, I must drive at a minimum speed of 120 miles per hour.