An 80-kg hiker climbs to the top of a tall hill and builds up 470,000 J of gravitational potential energy. How high did the hike
2 answers:
Answer:
599.5 m
Explanation:
The gain in gravitational potential energy of the man is given by:
where
m is the man's mass
g is the gravitational acceleration
is the change in height of the hiket
In this problem, we have the following data:
U = 470,000 J
g = 9.8 m/s^2
m = 80 kg
Solving the formula for , we find:
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Answer:
The speed is and the direction is heading north.
Explanation:
In collisions the force exerted by the objects that collide is higher enough than the external forces that we can neglect that external forces, with that assumption we can use the conservation fo momentum law that states, final total momentum (pf) is equal initial total momentum (pi) if there’re not external forces or they are small enough to be neglected. Mathematically:
The total momentum is the sum of the momentum of each of the bodies we're dealing, in our case the moment of each car, then:
with pn the momentum of the 1000kg car heading north and ps the 800kg car heading south. Momentum is defined as mass times velocity, then:
(1)
It's important to note that when we talk about momentum and velocity direction matters, so we're are going to choose a system of reference where quantities pointing north are positive and pointing south are negative. So, the initial velocity of 1000 kg car is vni=5 m/s, initial velocity of 800 kg car is vsi=-4 m/s and the final velocity of 1000 kg car is vnf=-1 m/s. Now we can solve (1) for vsf and use the values we already have:
Because the sign is positive the direction is to heading north.