Answer:
0.8m per second
Explanation:
we measure speed as distance over time
distance=8m
time=10s
therefore speed = 8/10
=0.8m per second
Answer:
f1 = 12.90 Hz
Explanation:
To calculate the first harmonic frequency you use the following formula for n = 1:

( 1 )
It is necessary that the unist are in meters, then you have:
L: length of the string = 60cm = 0.6m
M: mass of the string = 0.05kg
T: tension on the string = 20 N
you replace the values of L, M and T in the expression (1) for getting f1:

Hence, the first harmonic has a frequency of 12.90 Hz
Answer:
Explanation:
Given that,
The volume of the balloon is
V = 440 × 10³ m³
Buoyant force F?
Given the density of the surrounding to be 2.58 kg/m³
ρ = 2.58 kg/m³
The buoyant force is the weight of water displaced and it is calculated using
F_b = ρVg
Where
F_b is buoyant force
ρ is density
V is the volume of the liquid displace.
g is the acceleration due to gravity
Then,
F_b = ρVg
F_b = 2.58 × 440 × 10³ × 9.81
F_b = 1.1 × 10^7 N
Answer:
Speed of the ball relative to the boys: 25 km/h
Speed of the ball relative to a stationary observer: 35 km/h
Explanation:
The RV is travelling at a velocity of

Here we have taken the direction of motion of the RV as positive direction.
The boy sitting near the driver throws the ball back with speed of 25 km/h, so the velocity of the ball in the reference frame of the RV is

with negative sign since it is travelling in the opposite direction relative to the RV. Therefore, this is the velocity measured by every observer in the reference frame of the RV: so the speed measured by the boys is
v = 25 km/h
Instead, a stationary observer outside the RV measures a velocity of the ball given by the algebraic sum of the two velocities:
v = +60 km/h + (-25 km/h) = +35 km/h
So, he/she measures a speed of 35 km/h.