A cross-country skier can complete a 7.5km race in 45min. What is the skiers average speed?
2 answers:
Answer:
Average speed, v = 2.77 m/s
Explanation:
It is given that,
Distance to be covered in a race, d = 7.5 km = 7500 m
Time taken, t = 45 min = 2700 sec
We need to find the average speed of the skier. It can be calculated as :
v = 2.77 m/s
So, the skiers average speed of 2.77 m/s. Hence, this is the required solution.
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Answer:
a) 10.51 J
b) 3.48 m/s
Explanation:
Given data :
mass of train ( M ) = 2.2 kg
Given initial velocity ( u ) = 1.6 m/s
<u>a) calculating work done by the force over the journey of the train</u>
F = mx + b ------ ( 1 )
m = slope = ( Δ f / Δ x ) = 2.8 / -7.5 = - 0.373 N/m
x = distance travelled on the x axis by the train = 7.5 m
F = force experienced by the train = 2.8 N
x = 0
∴ b = 2.8
hence equation 1 can be written as
F = ( -0.373) x + 2.8 ----- ( 2 )
hence to determine the work done by the force
W = Note: the limits are actually 7.5 and 0
∴ W ( work done ) = -10.49 + 21 = 10.51 J
<u>b) calculate the speed of the train at the end of its journey</u>
we will apply the work energy theorem
W = 1/2 m*v^2 - 1/2 m*u^2
∴ V^2 = 2 / M ( W + 1/2 M*u^2 ) ( input values into equation )
V^2 = 12.11
hence V = 3.48 m/s
Answer:
Explanation:
The motion of ballistic pendulum is modelled by the appropriate use of the Principle of Energy Conservation:
The final velocity of the system formed by the ballistic pendulum and the bullet is:
Initial velocity of the bullet can be calculated from the expression derived of the Principle of Momentum: