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.
Answer:
6.136 mm
Explanation:
given,
frequency emitted by the bat = 5.59 x 10⁴ Hz
speed of sound = 343 m/s
smallest insect bat can hear will be equal to the wavelength of the sound the bat make.
λ = 6.136 mm
so, the smallest size of insect that bat can hear is equal to 6.136 mm
Answer:
(A) 7.9 m/s^{2}
(B) 19 m/s
(C) 91 m
Explanation:
initial velocity (U) = 0 mph = 0 m/s
final velocity (V) = 85 mph = 85 x 0.447 = 38 m/s
initial time (ti) = 0 s
final time (t) = 4.8 s
(A) acceleration = 
= 
= 7.9 m/s^{2}
(B) average velocity = 
=
= 19 m/s
(C) distance travelled (S) = ut + 
= (0 x 4.8) + 
= 91 m
potential energy = mass × gravity × height
so, change in potential energy = mass × gravity × change in height
2 = 50 × 10 × Δh
2 ÷ 500 = Δh
Δh = 0.004 m
This distance does depend on the initial velocity of the ball.
