A geologist is studying rock layers in an old river bed, and he finds a fossil of a fish and a horsetail rush in the same rock layer. According to the law of faunal and floral succession, the geologist can assume that the rock containing the fossils may date back as far as the <span>Devonian period</span>.
Answer:
1.5 km/s²
Explanation:
Given that:
a car starts from rest; it means the initial velocity (u) = 0 km/hr = 0 m/s
after time (t) = 20 seconds
the final velocity = 108 km/hr = 30 m/s
The acceleration (a) of the car can be determined by using the formula:



a = 1.5 km/s²
Explanation:
potential energy =360800J
mass(m)=?
height (h)=25m
g=9.8m/s²
we have
potential energy =360800J
mgh=360800J
m×9.8×25=360800
m=360800/(9.8×25)=1472.653061kg
Answer:
4.29 millimeters
Explanation:
Bats emit ultrasound waves: in air, ultrasound waves travel at a speed of

The frequency of the waves emitted by this bat is:

Therefore we can find the wavelength of the wave emitted by the bat by using the relationship between speed, frequency and wavelength:

Answer:
D. 2.5 Hz
Explanation:
Frequency = speed of wave / wavelength
= 335 /140 ( from graph)
= 2.4