It is given that by using track and cart we can record the time and the distance travelled and also the speed of the cart can be recorded. With all this data we can solve questions on the laws of motion.  
Like using the first law of motion we can determine the force of gravity acting on the cart that has moved a certain distance and the velocity or the speed of card has already been registered and since time is known putting the values in formula would help us calculate the gravitational pull acting on cart.
 
        
                    
             
        
        
        
Some of the most common examples of mechanical waves are water waves, sound waves, and seismic waves. There are three types of mechanical waves: transverse waves, longitudinal waves, and surface waves.
        
             
        
        
        
Answer:
Time, t = 0.015 seconds. 
Explanation:
Given the following data;
Mass, m = 0.2kg
Force, F = 200N
Initial velocity, u = 40m/s
Final velocity, v = 25m/s
To find the time;
Ft = m(v - u)
Time, t = m(v - u)/f
Substituting into the equation, we have;
Time, t = 0.2(25 - 40)/200
Time, t = 0.2(-15)/200
Time, t = 3/200
Time, t = 0.015 seconds.
Note: We ignored the negative sign because time can't be negative. 
 
        
             
        
        
        
Answer:
$893
Explanation: the complete question should be 
The clothes washer in your house consumes 470 kWh of energy per year. Price of the washer is $360 and the lifetime of the washer is 10 yrs. Energy price in your city is 9 cents per kWh. What is the lifecycle cost of the clothes washer? (assume a maintenance cost of $11 per year)
SOLUTION
Given: 
The clothes washe power consumption (PC) is 470 kWh
Price of the washer (P) is $360
lifetime of the washer (L) is 10 yrs
Energy price in the city (E) is 9 cents per kWh (Covert to $ by dividing 100)
maintenance cost (M) is $11 per year
Lifecycle cost = P + (PC × L × E) +M + L
Lifecycle cost = $360 + (470kWh × 10years × 9cents/100) + ($11 × 10years)
=$893
 
        
             
        
        
        
Frequency (f) = 500 hz (SI)
Velocity (V) = 1250 m/s (SI)
Wavelength (Lambda) = ? meters

