Answer:
2.13 x 10^-19 J or 0.53 eV
Explanation:
cut off wavelength, λo = 700 nm = 700 x 10^-9 m
λ = 400 nm = 400 x 10^-9 m
Use the energy equation
Where, K be the work function
K = 2.13 x 10^-19 J
K = 0.53 eV
Answer:
0.25 m/s
Explanation:
This problem can be solved by using the law of conservation of momentum - the total momentum of the squid-water system must be conserved.
Initially, the squid and the water are at rest, so the total momentum is zero:
After the squid ejects the water, the total momentum is
where
is the mass of the squid
is the velocity of the squid
is the mass of the water
is the velocity of the water
Due to the conservation of momentum,
so
so we can find the final velocity of the squid:
and the negative sign means the direction is opposite to that of the water.
I. Positive acceleration increases velocity. Negative acceleration decreases velocity. runner A sped up until the finish line and then slowed to a stop.
ii. Zero a acceleration implies a constant, unchanging velocity not a zero velocity. runner B achieved some velocity prior to 8s and is moving and must slow down to reach a stop.
iii. None. No aspects of this reasoning are correct. Everything she says is wrong. See iv for what/why.
iv. The sign on acceleration denotes the direction of *change in velocity* not change in direction. The sign on velocity can denote change in direction but only “forward” or “reverse” along a particular path. Cardinal direction is not indicated, generally, by the sign on velocity. It may correspond to North/South situationally but it is not an built-in feature of velocity and its sign. For example, if you are traveling with positive velocity and turn left to continue your journey you still have a positive velocity in the new direction. In fact, if you turn left again, traveling in the opposite direction as the one you started with your velocity would still be positive… in the new direction. The velocity relative to original direction could be said to be negative but that would be a confusing way to describe a journey. Maybe if you stopped the vehicle and moved in reverse, you could meaningfully say velocity was negative.
Answer:
The average velocity is 180 km/hr
Explanation:
Given;
initial velocity, u = 60 km per hour
final velocity, v = 120 km per hour
initial time = 1 hour
final time = 2 hour
Initial position = 60 km/h x 1 hour = 60 km
final position = 120 km/h x 2 hour = 240 km
The average velocity is given by;
Therefore, the average velocity is 180 km/hr
