6 3/7 * 1 5/9
45/7 * 14/9
630/63
10
        
                    
             
        
        
        
Answer:
The speed of the sled is 3.56 m/s
Explanation:
Given that,
Mass = 2.12 kg
Initial speed = 5.49 m/s
Coefficient of kinetic friction = 0.229
Distance = 3.89 m
We need to calculate the acceleration of sled
Using formula of acceleration

Where, F = frictional force
m = mass
Put the value into the formula




We need to calculate the speed of the sled
Using equation of motion

Where, v = final velocity
u = initial velocity
a = acceleration 
s = distance
Put the value in the equation



Hence, The speed of the sled is 3.56 m/s.
 
        
             
        
        
        
Answer: 2.7 m/s
Explanation:
Given the following :
Period (T) = 8.2 seconds 
Radius = 3.5 m
The tangential speed is given as:
V = Radius × ω
ω = angular speed = (2 × pi) / T
ω = (2 × 22/7) / 8.2
ω = 6.2857142 / 8.2
ω = 0.7665505
Therefore, tangential speed (V) equals;
r × ω
3.5 × 0.7665505 = 2.6829268 m/s
2.7 m/s 
 
        
             
        
        
        
Answer:
1.85c
Explanation:
a photon moves at c, the electron is moving at 0.85c, and since they are moving in opposing directions, the relative speed would be 1.85c
 
        
             
        
        
        
v = speed of car = 90 km/h
u = speed of truck = 50 km/h
d = initial separation distance = 100 m = 0.1 km
 
They meet at time t such that
 
vt = d + ut
 
t(v - u) = d
 
t = d/(v - u) = (0.1 km) / [(90 - 50) km/h] = 0.0025 hours