Answer:
because the book's is covered by papers
The magnitude of static friction force is f_s = 842.8 N
Explanation:
Write down the values given in the question
The wheel of a car has radius r = 0.350 m
The car applies the torque is τ = 295 N m
It is said that the wheels does not slip against the road surface,
Here we apply a force of static friction,
It can be calculated as
Frictional force f_s = τ / r
= 295 Nm / 0.350 m
f_s = 842.8 N
Given:
Mass of the rail road car, m = 2 kg
velocity of the three cars coupled system, v' = 1.20 m/s
velocity of first car,
= 3 m/s
Solution:
a) Momentum of a body of mass 'm' and velocity 'v' is given by:
p = mv
Now for the coupled system according to law of conservation of momentum, total momentum of a system before and after collision remain conserved:
(1)
where,
= velocity of the first car
= velocity of the 2 coupled cars after collision
Now, from eqn (1)


v' = 1.80 m/s
Therefore, the velocity of the combined car system after collision is 1.80 m/s
A Dodge Stealth is driving at 70 mph on a highway. It passes a BMW going the same direction. The BMW is moving 7 mph backward relative the Dodge. 63 mph is the velocity of the BMW
Answer: Option A
<u>Explanation:</u>
Given is the speed of the dodge stealth as 70 mph passing by the BMW moving with 7 mph relative to Dodge. Thereby, to calculate the velocity of BMW, relative velocity concept has to be employed.
As we know that the relative velocity tells us about relative velocity of mobile reference system as the difference or sum of the initial reference system.
Therefore,
velocity of the BMW = 
Velocity of the dodge = 
Velocity of the BMW with respect to dodge = 
As per the formula,

